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  • How do I draw a dotted or dashed line?

    - by Gagege
    I'm trying to draw a dashed or dotted line by placing individual segments(dashes) along a path and then separating them. The only algorithm I could come up with for this gave me a dash length that was variable based on the angle of the line. Like this: private function createDashedLine(fromX:Float, fromY:Float, toX:Float, toY:Float):Sprite { var line = new Sprite(); var currentX = fromX; var currentY = fromY; var addX = (toX - fromX) * 0.0075; var addY = (toY - fromY) * 0.0075; line.graphics.lineStyle(1, 0xFFFFFF); var count = 0; // while line is not complete while (!lineAtDestination(fromX, fromY, toX, toY, currentX, currentY)) { /// move line draw cursor to beginning of next dash line.graphics.moveTo(currentX, currentY); // if dash is even if (count % 2 == 0) { // draw the dash line.graphics.lineTo(currentX + addX, currentY + addY); } // add next dash's length to current cursor position currentX += addX; currentY += addY; count++; } return line; } This just happens to be written in Haxe, but the solution should be language neutral. What I would like is for the dash length to be the same no matter what angle the line is. As is, it's just adding 75 thousandths of the line length to the x and y, so if the line is and a 45 degree angle you get pretty much a solid line. If the line is at something shallow like 85 degrees then you get a nice looking dashed line. So, the dash length is variable, and I don't want that. How would I make a function that I can pass a "dash length" into and get that length of dash, no matter what the angle is? If you need to completely disregard my code, be my guest. I'm sure there's a better solution.

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  • Dynamic Jump spot

    - by Pasquale Sada
    I have an initial velocity V(Vx,Vy,VZ) and a spot where he stands still at S(Sx,Sy,Sz). What I'm trying to achieve is a jump on a spot E(Ex,Ey,Ez) where you have clicked on(only lower or higher spot, because I've in place a simple steering behavior for even terrains). There are no obstacle around. I've implemented a formula that can make him jump in a precise way on a spot but you need to declare an angle: the problem arise when the selected spot is straight above your head. It' pretty lame that the char hang there and can reach a thing that is 1cm above is head. I'll share the code I'm using: Vector3 dir = target - transform.position; // get target direction float h = dir.y; // get height difference dir.y = 0; // retain only the horizontal direction float dist = dir.magnitude ; // get horizontal distance float a = angle * Mathf.Deg2Rad; // convert angle to radians dir.y = dist * Mathf.Tan(a); // set dir to the elevation angle dist += h / Mathf.Tan(a); // correct for small height differences // calculate the velocity magnitude float vel = Mathf.Sqrt(dist * Physics.gravity.magnitude / Mathf.Sin(2 *a)); return vel * dir.normalized;

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  • Moving an object using its velocity on a closed curve

    - by Futaro
    I want that an object follows a path, in Peggle game there are some pegs that have movement in a closed path. How can i get the same result? I guess that I can use parametric curve but I need use the velocity and not the position (x, y). I use NAPE and I have this in my gameloop: //circunference angle = angle + 1*(Math.PI / 180); movableBall.position.x = radius * Math.cos(angle)+ h; movableBall.position.y = radius * Math.sin(angle)+ k; it's works but I can not control the velocity, each movableBall must have its own velocity. Besides, from docs of NAPE:"Setting the position of a body is equivalent to simply teleporting the body; for instance moving a kinematic body by position is not the way to go about things.." I want to use: movableBall.velocity.x =?? movableBall.velocity.y = ?? The final idea is to follow others paths like the Lemniscate of Bernoulli. Thanks!

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  • List has no value after adding values in

    - by Sigh-AniDe
    I am creating a a ghost sprite that will mimic the main sprite after 10 seconds of the game. I am storing the users movements in a List<string> and i am using a foreach loop to run the movements. The problem is when i run through the game by adding breakpoints the movements are being added to the List<string> but when the foreach runs it shows that the list has nothing in it. Why does it do that? How can i fix it? this is what i have: public List<string> ghostMovements = new List<string>(); public void UpdateGhost(float scalingFactor, int[,] map) { // At this foreach, ghostMovements has nothing in it foreach (string s in ghostMovements) { // current position of the ghost on the tiles int mapX = (int)(ghostPostition.X / scalingFactor); int mapY = (int)(ghostPostition.Y / scalingFactor); if (s == "left") { switch (ghostDirection) { case ghostFacingUp: angle = 1.6f; ghostDirection = ghostFacingRight; Program.form.direction = ""; break; case ghostFacingRight: angle = 3.15f; ghostDirection = ghostFacingDown; Program.form.direction = ""; break; case ghostFacingDown: angle = -1.6f; ghostDirection = ghostFacingLeft; Program.form.direction = ""; break; case ghostFacingLeft: angle = 0.0f; ghostDirection = ghostFacingUp; Program.form.direction = ""; break; } } } } // The movement is captured here and added to the list public void captureMovement() { ghostMovements.Add(Program.form.direction); }

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  • Open GL stars are not rendering

    - by Darestium
    I doing Nehe's Open GL Lesson 9. I'm using SFML for windowing, the strange thing is no stars are rendering. #include <SFML/System.hpp> #include <SFML/Window.hpp> #include <SFML/Graphics.hpp> #include <iostream> void processEvents(sf::Window *app); void processInput(sf::Window *app); void renderGlScene(sf::Window *app); void init(); int loadResources(); const int NUM_OF_STARS = 50; float triRot = 0.0f; float quadRot = 0.0f; bool twinkle = false; bool tKey = false; float zoom = 15.0f; float tilt = 90.0f; float spin = 0.0f; unsigned int loop; unsigned int texture_handle[1]; typedef struct { int r, g, b; float distance; float angle; } stars; stars star[NUM_OF_STARS]; int main() { sf::Window app(sf::VideoMode(800, 600, 32), "Nehe Lesson 9"); app.UseVerticalSync(false); init(); if (loadResources() == -1) { return EXIT_FAILURE; } while (app.IsOpened()) { processEvents(&app); processInput(&app); renderGlScene(&app); app.Display(); } return EXIT_SUCCESS; } int loadResources() { sf::Image img_data; // Load Texture if (!img_data.LoadFromFile("data/images/star.bmp")) { std::cout << "Could not load data/images/star.bmp"; return -1; } // Generate 1 texture glGenTextures(1, &texture_handle[0]); // Linear filtering glBindTexture(GL_TEXTURE_2D, texture_handle[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img_data.GetWidth(), img_data.GetHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img_data.GetPixelsPtr()); return 0; } void processInput(sf::Window *app) { const sf::Input& input = app->GetInput(); if (input.IsKeyDown(sf::Key::T) && !tKey) { tKey = true; twinkle = !twinkle; } if (!input.IsKeyDown(sf::Key::T)) { tKey = false; } if (input.IsKeyDown(sf::Key::Up)) { tilt -= 0.05f; } if (input.IsKeyDown(sf::Key::Down)) { tilt += 0.05f; } if (input.IsKeyDown(sf::Key::PageUp)) { zoom -= 0.02f; } if (input.IsKeyDown(sf::Key::Up)) { zoom += 0.02f; } } void init() { glClearDepth(1.f); glClearColor(0.f, 0.f, 0.f, 0.f); // Enable texturing glEnable(GL_TEXTURE_2D); //glDepthMask(GL_TRUE); // Setup a perpective projection glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.f, 1.f, 1.f, 500.f); glShadeModel(GL_SMOOTH); glBlendFunc(GL_SRC_ALPHA, GL_ONE); glEnable(GL_BLEND); for (loop = 0; loop < NUM_OF_STARS; loop++) { star[loop].distance = (float)loop / NUM_OF_STARS * 5.0f; // Calculate distance from the centre // Give stars random rgb value star[loop].r = rand() % 256; star[loop].g = rand() % 256; star[loop].b = rand() % 256; } } void processEvents(sf::Window *app) { sf::Event event; while (app->GetEvent(event)) { if (event.Type == sf::Event::Closed) { app->Close(); } if (event.Type == sf::Event::KeyPressed && event.Key.Code == sf::Key::Escape) { app->Close(); } } } void renderGlScene(sf::Window *app) { app->SetActive(); // Clear color depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Apply some transformations glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // Select texture glBindTexture(GL_TEXTURE_2D, texture_handle[0]); for (loop = 0; loop < NUM_OF_STARS; loop++) { glLoadIdentity(); // Reset The View Before We Draw Each Star glTranslatef(0.0f, 0.0f, zoom); // Zoom Into The Screen (Using The Value In 'zoom') glRotatef(tilt, 1.0f, 0.0f, 0.0f); // Tilt The View (Using The Value In 'tilt') glRotatef(star[loop].angle, 0.0f, 1.0f, 0.0f); // Rotate To The Current Stars Angle glTranslatef(star[loop].distance, 0.0f, 0.0f); // Move Forward On The X Plane glRotatef(-star[loop].angle,0.0f,1.0f,0.0f); // Cancel The Current Stars Angle glRotatef(-tilt,1.0f,0.0f,0.0f); // Cancel The Screen Tilt if (twinkle) { glColor4ub(star[(NUM_OF_STARS - loop) - 1].r, star[(NUM_OF_STARS - loop)-1].g, star[(NUM_OF_STARS - loop) - 1].b, 255); glBegin(GL_QUADS); // Begin Drawing The Textured Quad glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f); glEnd(); // Done Drawing The Textured Quad } glRotatef(spin,0.0f,0.0f,1.0f); // Rotate The Star On The Z Axis // Assign A Color Using Bytes glColor4ub(star[loop].r, star[loop].g, star[loop].b, 255); glBegin(GL_QUADS); // Begin Drawing The Textured Quad glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f); glEnd(); // Done Drawing The Textured Quad spin += 0.01f; // Used To Spin The Stars star[loop].angle += (float)loop / NUM_OF_STARS; // Changes The Angle Of A Star star[loop].distance -= 0.01f; // Changes The Distance Of A Star if (star[loop].distance < 0.0f) { star[loop].distance += 5.0f; // Move The Star 5 Units From The Center star[loop].r = rand() % 256; // Give It A New Red Value star[loop].g = rand() % 256; // Give It A New Green Value star[loop].b = rand() % 256; // Give It A New Blue Value } } } I've looked over the code atleast 10 times now and I can't figure out the problem. Any help would be much appreciated.

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  • Is there a Math.atan2 substitute for j2ME? Blackberry development

    - by Kai
    I have a wide variety of locations stored in my persistent object that contain latitudes and longitudes in double(43.7389, 7.42577) format. I need to be able to grab the user's latitude and longitude and select all items within, say 1 mile. Walking distance. I have done this in PHP so I snagged my PHP code and transferred it to Java, where everything plugged in fine until I figured out J2ME doesn't support atan2(double, double). So, after some searching, I find a small snippet of code that is supposed to be a substitute for atan2. Here is the code: public double atan2(double y, double x) { double coeff_1 = Math.PI / 4d; double coeff_2 = 3d * coeff_1; double abs_y = Math.abs(y)+ 1e-10f; double r, angle; if (x >= 0d) { r = (x - abs_y) / (x + abs_y); angle = coeff_1; } else { r = (x + abs_y) / (abs_y - x); angle = coeff_2; } angle += (0.1963f * r * r - 0.9817f) * r; return y < 0.0f ? -angle : angle; } I am getting odd results from this. My min and max latitude and longitudes are coming back as incredibly low numbers that can't possibly be right. Like 0.003785746 when I am expecting something closer to the original lat and long values (43.7389, 7.42577). Since I am no master of advanced math, I don't really know what to look for here. Perhaps someone else may have an answer. Here is my complete code: package store_finder; import java.util.Vector; import javax.microedition.location.Criteria; import javax.microedition.location.Location; import javax.microedition.location.LocationException; import javax.microedition.location.LocationListener; import javax.microedition.location.LocationProvider; import javax.microedition.location.QualifiedCoordinates; import net.rim.blackberry.api.invoke.Invoke; import net.rim.blackberry.api.invoke.MapsArguments; import net.rim.device.api.system.Bitmap; import net.rim.device.api.system.Display; import net.rim.device.api.ui.Color; import net.rim.device.api.ui.Field; import net.rim.device.api.ui.Graphics; import net.rim.device.api.ui.Manager; import net.rim.device.api.ui.component.BitmapField; import net.rim.device.api.ui.component.RichTextField; import net.rim.device.api.ui.component.SeparatorField; import net.rim.device.api.ui.container.HorizontalFieldManager; import net.rim.device.api.ui.container.MainScreen; import net.rim.device.api.ui.container.VerticalFieldManager; public class nearBy extends MainScreen { private HorizontalFieldManager _top; private VerticalFieldManager _middle; private int horizontalOffset; private final static long animationTime = 300; private long animationStart = 0; private double latitude = 43.7389; private double longitude = 7.42577; private int _interval = -1; private double max_lat; private double min_lat; private double max_lon; private double min_lon; private double latitude_in_degrees; private double longitude_in_degrees; public nearBy() { super(); horizontalOffset = Display.getWidth(); _top = new HorizontalFieldManager(Manager.USE_ALL_WIDTH | Field.FIELD_HCENTER) { public void paint(Graphics gr) { Bitmap bg = Bitmap.getBitmapResource("bg.png"); gr.drawBitmap(0, 0, Display.getWidth(), Display.getHeight(), bg, 0, 0); subpaint(gr); } }; _middle = new VerticalFieldManager() { public void paint(Graphics graphics) { graphics.setBackgroundColor(0xFFFFFF); graphics.setColor(Color.BLACK); graphics.clear(); super.paint(graphics); } protected void sublayout(int maxWidth, int maxHeight) { int displayWidth = Display.getWidth(); int displayHeight = Display.getHeight(); super.sublayout( displayWidth, displayHeight); setExtent( displayWidth, displayHeight); } }; add(_top); add(_middle); Bitmap lol = Bitmap.getBitmapResource("logo.png"); BitmapField lolfield = new BitmapField(lol); _top.add(lolfield); Criteria cr= new Criteria(); cr.setCostAllowed(true); cr.setPreferredResponseTime(60); cr.setHorizontalAccuracy(5000); cr.setVerticalAccuracy(5000); cr.setAltitudeRequired(true); cr.isSpeedAndCourseRequired(); cr.isAddressInfoRequired(); try{ LocationProvider lp = LocationProvider.getInstance(cr); if( lp!=null ){ lp.setLocationListener(new LocationListenerImpl(), _interval, 1, 1); } } catch(LocationException le) { add(new RichTextField("Location exception "+le)); } //_middle.add(new RichTextField("this is a map " + Double.toString(latitude) + " " + Double.toString(longitude))); int lat = (int) (latitude * 100000); int lon = (int) (longitude * 100000); String document = "<location-document>" + "<location lon='" + lon + "' lat='" + lat + "' label='You are here' description='You' zoom='0' />" + "<location lon='742733' lat='4373930' label='Hotel de Paris' description='Hotel de Paris' address='Palace du Casino' postalCode='98000' phone='37798063000' zoom='0' />" + "</location-document>"; // Invoke.invokeApplication(Invoke.APP_TYPE_MAPS, new MapsArguments( MapsArguments.ARG_LOCATION_DOCUMENT, document)); _middle.add(new SeparatorField()); surroundingVenues(); _middle.add(new RichTextField("max lat: " + max_lat)); _middle.add(new RichTextField("min lat: " + min_lat)); _middle.add(new RichTextField("max lon: " + max_lon)); _middle.add(new RichTextField("min lon: " + min_lon)); } private void surroundingVenues() { double point_1_latitude_in_degrees = latitude; double point_1_longitude_in_degrees= longitude; // diagonal distance + error margin double distance_in_miles = (5 * 1.90359441) + 10; getCords (point_1_latitude_in_degrees, point_1_longitude_in_degrees, distance_in_miles, 45); double lat_limit_1 = latitude_in_degrees; double lon_limit_1 = longitude_in_degrees; getCords (point_1_latitude_in_degrees, point_1_longitude_in_degrees, distance_in_miles, 135); double lat_limit_2 = latitude_in_degrees; double lon_limit_2 = longitude_in_degrees; getCords (point_1_latitude_in_degrees, point_1_longitude_in_degrees, distance_in_miles, -135); double lat_limit_3 = latitude_in_degrees; double lon_limit_3 = longitude_in_degrees; getCords (point_1_latitude_in_degrees, point_1_longitude_in_degrees, distance_in_miles, -45); double lat_limit_4 = latitude_in_degrees; double lon_limit_4 = longitude_in_degrees; double mx1 = Math.max(lat_limit_1, lat_limit_2); double mx2 = Math.max(lat_limit_3, lat_limit_4); max_lat = Math.max(mx1, mx2); double mm1 = Math.min(lat_limit_1, lat_limit_2); double mm2 = Math.min(lat_limit_3, lat_limit_4); min_lat = Math.max(mm1, mm2); double mlon1 = Math.max(lon_limit_1, lon_limit_2); double mlon2 = Math.max(lon_limit_3, lon_limit_4); max_lon = Math.max(mlon1, mlon2); double minl1 = Math.min(lon_limit_1, lon_limit_2); double minl2 = Math.min(lon_limit_3, lon_limit_4); min_lon = Math.max(minl1, minl2); //$qry = "SELECT DISTINCT zip.zipcode, zip.latitude, zip.longitude, sg_stores.* FROM zip JOIN store_finder AS sg_stores ON sg_stores.zip=zip.zipcode WHERE zip.latitude<=$lat_limit_max AND zip.latitude>=$lat_limit_min AND zip.longitude<=$lon_limit_max AND zip.longitude>=$lon_limit_min"; } private void getCords(double point_1_latitude, double point_1_longitude, double distance, int degs) { double m_EquatorialRadiusInMeters = 6366564.86; double m_Flattening=0; double distance_in_meters = distance * 1609.344 ; double direction_in_radians = Math.toRadians( degs ); double eps = 0.000000000000005; double r = 1.0 - m_Flattening; double point_1_latitude_in_radians = Math.toRadians( point_1_latitude ); double point_1_longitude_in_radians = Math.toRadians( point_1_longitude ); double tangent_u = (r * Math.sin( point_1_latitude_in_radians ) ) / Math.cos( point_1_latitude_in_radians ); double sine_of_direction = Math.sin( direction_in_radians ); double cosine_of_direction = Math.cos( direction_in_radians ); double heading_from_point_2_to_point_1_in_radians = 0.0; if ( cosine_of_direction != 0.0 ) { heading_from_point_2_to_point_1_in_radians = atan2( tangent_u, cosine_of_direction ) * 2.0; } double cu = 1.0 / Math.sqrt( ( tangent_u * tangent_u ) + 1.0 ); double su = tangent_u * cu; double sa = cu * sine_of_direction; double c2a = ( (-sa) * sa ) + 1.0; double x= Math.sqrt( ( ( ( 1.0 /r /r ) - 1.0 ) * c2a ) + 1.0 ) + 1.0; x= (x- 2.0 ) / x; double c= 1.0 - x; c= ( ( (x * x) / 4.0 ) + 1.0 ) / c; double d= ( ( 0.375 * (x * x) ) -1.0 ) * x; tangent_u = distance_in_meters /r / m_EquatorialRadiusInMeters /c; double y= tangent_u; boolean exit_loop = false; double cosine_of_y = 0.0; double cz = 0.0; double e = 0.0; double term_1 = 0.0; double term_2 = 0.0; double term_3 = 0.0; double sine_of_y = 0.0; while( exit_loop != true ) { sine_of_y = Math.sin(y); cosine_of_y = Math.cos(y); cz = Math.cos( heading_from_point_2_to_point_1_in_radians + y); e = (cz * cz * 2.0 ) - 1.0; c = y; x = e * cosine_of_y; y = (e + e) - 1.0; term_1 = ( sine_of_y * sine_of_y * 4.0 ) - 3.0; term_2 = ( ( term_1 * y * cz * d) / 6.0 ) + x; term_3 = ( ( term_2 * d) / 4.0 ) -cz; y= ( term_3 * sine_of_y * d) + tangent_u; if ( Math.abs(y - c) > eps ) { exit_loop = false; } else { exit_loop = true; } } heading_from_point_2_to_point_1_in_radians = ( cu * cosine_of_y * cosine_of_direction ) - ( su * sine_of_y ); c = r * Math.sqrt( ( sa * sa ) + ( heading_from_point_2_to_point_1_in_radians * heading_from_point_2_to_point_1_in_radians ) ); d = ( su * cosine_of_y ) + ( cu * sine_of_y * cosine_of_direction ); double point_2_latitude_in_radians = atan2(d, c); c = ( cu * cosine_of_y ) - ( su * sine_of_y * cosine_of_direction ); x = atan2( sine_of_y * sine_of_direction, c); c = ( ( ( ( ( -3.0 * c2a ) + 4.0 ) * m_Flattening ) + 4.0 ) * c2a * m_Flattening ) / 16.0; d = ( ( ( (e * cosine_of_y * c) + cz ) * sine_of_y * c) + y) * sa; double point_2_longitude_in_radians = ( point_1_longitude_in_radians + x) - ( ( 1.0 - c) * d * m_Flattening ); heading_from_point_2_to_point_1_in_radians = atan2( sa, heading_from_point_2_to_point_1_in_radians ) + Math.PI; latitude_in_degrees = Math.toRadians( point_2_latitude_in_radians ); longitude_in_degrees = Math.toRadians( point_2_longitude_in_radians ); } public double atan2(double y, double x) { double coeff_1 = Math.PI / 4d; double coeff_2 = 3d * coeff_1; double abs_y = Math.abs(y)+ 1e-10f; double r, angle; if (x >= 0d) { r = (x - abs_y) / (x + abs_y); angle = coeff_1; } else { r = (x + abs_y) / (abs_y - x); angle = coeff_2; } angle += (0.1963f * r * r - 0.9817f) * r; return y < 0.0f ? -angle : angle; } private Vector fetchVenues(double max_lat, double min_lat, double max_lon, double min_lon) { return new Vector(); } private class LocationListenerImpl implements LocationListener { public void locationUpdated(LocationProvider provider, Location location) { if(location.isValid()) { nearBy.this.longitude = location.getQualifiedCoordinates().getLongitude(); nearBy.this.latitude = location.getQualifiedCoordinates().getLatitude(); //double altitude = location.getQualifiedCoordinates().getAltitude(); //float speed = location.getSpeed(); } } public void providerStateChanged(LocationProvider provider, int newState) { // MUST implement this. Should probably do something useful with it as well. } } } please excuse the mess. I have the user lat long hard coded since I do not have GPS functional yet. You can see the SQL query commented out to know how I plan on using the min and max lat and long values. Any help is appreciated. Thanks

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  • Parabolic throw with set Height and range (libgdx)

    - by Tauboga
    Currently i'm working on a minigame for android where you have a rotating ball in the center of the display which jumps when touched in the direction of his current angle. I'm simply using a gravity vector and a velocity vector in this way: positionBall = positionBall.add(velocity); velocity = velocity.add(gravity); and velocity.x = (float) Math.cos(angle) * 12; /* 12 to amplify the velocity */ velocity.y = (float) Math.sin(angle) * 15; /* 15 to amplify the velocity */ That works fine. Here comes the problem: I want to make the jump look the same on all possible resolutions. The velocity needs to be scaled in a way that when the ball is thrown straight upwards it will touch the upper display border. When thrown directly left or right the range shall be exactly long enough to touch the left/right display border. Which formula(s) do I need to use and how to implement them correctly? Thanks in advance!

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  • How to Align Gun with Bullets

    - by Shane
    I have a top-down 2D shooter. I have an image of a player holding a gun, that rotates to face the mouse. Please note that the gun isn't a separate image tethered to the player, but rather part of the player. Right now, bullets are created at the player's x and y. This works when the player is facing the right way, but not when they rotate. The bullets move in the right direction, but don't come from the gun. How can I fix this? TL;DR: When the player rotates, bullets don't come from gun. public void fire() { angle = sprite.getRotation(); System.out.println(angle); x = sprite.getX(); y = sprite.getY(); Bullet b = new Bullet(x, y, angle); Utils.world.addBullet(b); }

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  • Calculate vector direction

    - by Starkers
    Is the direction angle always measured from the plus x axis? Does a vector in the +,+ quadrant always have a direction between 0 and 90, and in -,+ between 90 and 180 and in -,- between 180 and 270 and in -,+ between 270 and 360 ? Also, how should we calculate the direction using tan? Would that mean nested if statements to find out what quadrant we're in, and then applying the appropriate "work arounds"? E.g. If we were in the -,+ (like in the diagram) would we find the angle from the + axis would be 90 + tan^-1(y/x), the 90 + only used because we're in the -,+ quadrant. Also, that's just a quick solution, may be off, I just want to know if we use nested if statements to get the angle from the + x axis. Finally, should we find the distance in degrees or radians?

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  • Calculate random points (pixel) within a circle (image)

    - by DMills
    I have an image that contains a circles at a specific location, and of a specific diameter. What I need to do is to be able to calculate random points within the circle, and then manipulate said the pixels they correlate to. I have the following code already: private Point CalculatePoint() { var angle = _random.NextDouble() * ( Math.PI * 2 ); var x = _originX + ( _radius * Math.Cos( angle ) ); var y = _originY + ( _radius * Math.Sin( angle ) ); return new Point( ( int )x, ( int )y ); } And that works fine for finding all the points at the circumference of the circle, but I need all points from anywhere in the circle. If this doesn't make sense let me know and I will do my best to clarify.

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  • emo-framework in android move on collision of sprites with physics

    - by KaHeL
    I'm developing my first ever game for Android where I'm still learning about using of framework. To begin I made two sprites of ball where one ball is movable by dragging and another one is just standing on it's place on load. Now I've already added the collision listener for both sprites and as tested it's working properly. Now what I need to learn is on how can I add physics on both sprites where when they collide the standing sprite will move based on the physics and bounce around the screen. It would be best if you teach it to me step by step since I'm a little slow on this. Here's my nut so far: local stage = emo.Stage(); class Okay_1 { sprite = null; spriteok = null; dragStart = false; angle = 0; // Called when the stage is loaded function onLoad() { print("Level_1 is loaded!"); // Create new sprite and load 'f1.png' sprite = emo.Sprite("f1.png"); sprite.moveCenter(stage.getWindowWidth() * 0.5, stage.getWindowHeight() * 0.5); sprite.load(); spriteok = emo.Sprite("okay.png") spriteok.setWidth(100); spriteok.setHeight(100); spriteok.load(); // Check if the coordinate (X=100, Y=100) is inside the sprite if (spriteok.contains(100, 100)) { print("contains!"); } // Does the sprite collides with the other sprite? if (spriteok.collidesWith(sprite)) { print("collides!"); } } function onMotionEvent(ev) { if (ev.getAction() == MOTION_EVENT_ACTION_DOWN) { // Moves the sprite at the position of motion event angle = sprite.getAngle(); sprite.remove(); sprite = emo.Sprite("f2.png"); sprite.load(); sprite.rotate(angle); sprite.moveCenter(ev.getX(), ev.getY()); sprite.rotate(sprite.getAngle()+10); // Check if the coordinate (X=100, Y=100) is inside the sprite if (sprite.contains(sprite.getWidth(), sprite.getHeight())) { print("contains!"); } // Does the sprite collides with the other sprite? if (sprite.collidesWith(spriteok)) { print("collides!"); } dragStart = true; }else if (ev.getAction() == MOTION_EVENT_ACTION_MOVE) { if (dragStart) { // Moves the sprite at the position of motion event sprite.moveCenter(ev.getX(), ev.getY()); sprite.rotate(sprite.getAngle()+10); // Check if the coordinate (X=100, Y=100) is inside the sprite if (sprite.contains(sprite.getWidth(), sprite.getHeight())) { print("contains!"); } // Does the sprite collides with the other sprite? if (sprite.collidesWith(spriteok)) { print("collides!"); } } }else if (ev.getAction() == MOTION_EVENT_ACTION_UP || ev.getAction() == MOTION_EVENT_ACTION_CANCEL) { if (dragStart) { // change block color to red dragStart = false; angle = sprite.getAngle(); sprite.remove(); sprite = emo.Sprite("f1.png"); sprite.load(); sprite.moveCenter(ev.getX(), ev.getY()); sprite.rotate(angle); // Check if the coordinate (X=100, Y=100) is inside the sprite if (sprite.contains(sprite.getWidth(), sprite.getHeight())) { print("contains!"); } // Does the sprite collides with the other sprite? if (sprite.collidesWith(spriteok)) { print("collides!"); } } } } // Called when the stage is disposed function onDispose() { sprite.remove(); // Remove the sprite print("Level_1 is disposed!"); } } function emo::onLoad() { emo.Stage().load(Okay_1()); }

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  • Implementing touch-based rotation in cocoa touch

    - by ewoo
    I am wondering what is the best way to implement rotation-based dragging movements in my iPhone application. I have a UIView that I wish to rotate around its centre, when the users finger is touch the view and they move it. Think of it like a dial that needs to be adjusted with the finger. The basic question comes down to: 1) Should I remember the initial angle and transform when touchesBegan is called, and then every time touchesMoved is called apply a new transform to the view based on the current position of the finger, e.g., something like: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self]; //current position of touch if (([touch view] == self) && [Utility getDistance:currentPoint toPoint:self.middle] <= ROTATE_RADIUS //middle is centre of view && [Utility getDistance:currentPoint toPoint:self.middle] >= MOVE_RADIUS) { //will be rotation gesture //remember state of view at beginning of touch CGPoint top = CGPointMake(self.middle.x, 0); self.initialTouch = currentPoint; self.initialAngle = angleBetweenLines(self.middle, top, self.middle, currentPoint); self.initialTransform = self.transform; } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self]; //current position of touch if (([touch view] == self) && [Utility getDistance:currentPoint toPoint:self.middle] <= ROTATE_RADIUS && [Utility getDistance:currentPoint toPoint:self.middle] >= MOVE_RADIUS) { //a rotation gesture //rotate tile float newAngle = angleBetweenLines(self.middle, CGPointMake(self.middle.x, 0), self.middle, currentPoint); //touch angle float angleDif = newAngle - self.initialAngle; //work out dif between angle at beginning of touch and now. CGAffineTransform newTransform = CGAffineTransformRotate(self.initialTransform, angleDif); //create new transform self.transform = newTransform; //apply transform. } OR 2) Should I simply remember the last known position/angle, and rotate the view based on the difference in angle between that and now, e.g.,: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self]; //current position of touch if (([touch view] == self) && [Utility getDistance:currentPoint toPoint:self.middle] <= ROTATE_RADIUS && [Utility getDistance:currentPoint toPoint:self.middle] >= MOVE_RADIUS) { //will be rotation gesture //remember state of view at beginning of touch CGPoint top = CGPointMake(self.middle.x, 0); self.lastTouch = currentPoint; self.lastAngle = angleBetweenLines(self.middle, top, self.middle, currentPoint); } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self]; //current position of touch if (([touch view] == self) && [Utility getDistance:currentPoint toPoint:middle] <= ROTATE_RADIUS && [Utility getDistance:currentPoint toPoint:middle] >= MOVE_RADIUS) { //a rotation gesture //rotate tile float newAngle = angleBetweenLines(self.middle, CGPointMake(self.middle.x, 0), self.middle, currentPoint); //touch angle float angleDif = newAngle - self.lastAngle; //work out dif between angle at beginning of touch and now. CGAffineTransform newTransform = CGAffineTransformRotate(self.transform, angleDif); //create new transform self.transform = newTransform; //apply transform. self.lastTouch = currentPoint; self.lastAngle = newAngle; } The second option makes more sense to me, but it is not giving very pleasing results (jaggy updates and non-smooth rotations). Which way is best (if any), in terms of performance? Cheers!

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  • Creating a UIImage from a rotated UIImageView...

    - by Magic Bullet Dave
    I have a UIImageView with an image in it. I have rotated the image prior to display by setting the transform property of the UIImageView to CGAffineTransformMakeRotation(angle) where angle is the angle in radians. I want to be able to create another UIImage that corresponds to the rotated version that I can see in my view. I am almost there, by rotating the image context I get a rotated image: - (UIImage *) rotatedImageFromImageView: (UIImageView *) imageView { UIImage *rotatedImage; // Get image width, height of the bonuding rectangle CGRect boundingRect = [self getBoundingRectAfterRotation: imageView.bounds byAngle:angle]; // Create a graphics context the size of the boundinf rectangle UIGraphicsBeginImageContext(boundingRect.size); CGContextRef context = UIGraphicsGetCurrentContext(); // Rotate and translate the context CGAffineTransform ourTransform = CGAffineTransformIdentity; ourTransform = CGAffineTransformConcat(ourTransform, CGAffineTransformMakeRotation(angle)); CGContextConcatCTM(context, ourTransform); // Draw the image into the context CGContextDrawImage(context, CGRectMake(0, 0, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage); // Get an image from the context rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)]; // Clean up UIGraphicsEndImageContext(); return rotatedImage; } However the image is not rotated about its centre. I have tried all kinds of transforms concatenated with my rotate to get it to rotate around the centre but to no avail. Am I missing a trick? Is this even possible since I am rotating the context not the image? Getting desperate to make this work now, so any help would be appreciated. Dave

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  • Bounding Boxes for Circle and Arcs in 3D

    - by David Rutten
    Given curves of type Circle and Circular-Arc in 3D space, what is a good way to compute accurate bounding boxes (world axis aligned)? Edit: found solution for circles, still need help with Arcs. C# snippet for solving BoundingBoxes for Circles: public static BoundingBox CircleBBox(Circle circle) { Point3d O = circle.Center; Vector3d N = circle.Normal; double ax = Angle(N, new Vector3d(1,0,0)); double ay = Angle(N, new Vector3d(0,1,0)); double az = Angle(N, new Vector3d(0,0,1)); Vector3d R = new Vector3d(Math.Sin(ax), Math.Sin(ay), Math.Sin(az)); R *= circle.Radius; return new BoundingBox(O - R, O + R); } private static double Angle(Vector3d A, Vector3d B) { double dP = A * B; if (dP <= -1.0) { return Math.PI; } if (dP >= +1.0) { return 0.0; } return Math.Acos(dP); }

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  • Class Self-Reference

    - by Free Bullets
    I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this? class MyScannedRobotEvent extends robocode.ScannedRobotEvent { public int angle(robocode.Robot myRobot) { return (int) Math.toRadians((myRobot.getHeading() + getBearing()) % 360); } } public class MyRobot extends robocode.Robot { int a = angle(**WHATDOIPUTHERE?**) }

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  • physics game programming box2d - orientating a turret-like object using torques

    - by egarcia
    This is a problem I hit when trying to implement a game using the LÖVE engine, which covers box2d with Lua scripting. The objective is simple: A turret-like object (seen from the top, on a 2D environment) needs to orientate itself so it points to a target. The turret is on the x,y coordinates, and the target is on tx, ty. We can consider that x,y are fixed, but tx, ty tend to vary from one instant to the other (i.e. they would be the mouse cursor). The turret has a rotor that can apply a rotational force (torque) on any given moment, clockwise or counter-clockwise. The magnitude of that force has an upper limit called maxTorque. The turret also has certain rotational inertia, which acts for angular movement the same way mass acts for linear movement. There's no friction of any kind, so the turret will keep spinning if it has an angular velocity. The turret has a small AI function that re-evaluates its orientation to verify that it points to the right direction, and activates the rotator. This happens every dt (~60 times per second). It looks like this right now: function Turret:update(dt) local x,y = self:getPositon() local tx,ty = self:getTarget() local maxTorque = self:getMaxTorque() -- max force of the turret rotor local inertia = self:getInertia() -- the rotational inertia local w = self:getAngularVelocity() -- current angular velocity of the turret local angle = self:getAngle() -- the angle the turret is facing currently -- the angle of the like that links the turret center with the target local targetAngle = math.atan2(oy-y,ox-x) local differenceAngle = _normalizeAngle(targetAngle - angle) if(differenceAngle <= math.pi) then -- counter-clockwise is the shortest path self:applyTorque(maxTorque) else -- clockwise is the shortest path self:applyTorque(-maxTorque) end end ... it fails. Let me explain with two illustrative situations: The turret "oscillates" around the targetAngle. If the target is "right behind the turret, just a little clock-wise", the turret will start applying clockwise torques, and keep applying them until the instant in which it surpasses the target angle. At that moment it will start applying torques on the opposite direction. But it will have gained a significant angular velocity, so it will keep going clockwise for some time... until the target will be "just behind, but a bit counter-clockwise". And it will start again. So the turret will oscillate or even go in round circles. I think that my turret should start applying torques in the "opposite direction of the shortest path" before it reaches the target angle (like a car braking before stopping). Intuitively, I think the turret should "start applying torques on the opposite direction of the shortest path when it is about half-way to the target objective". My intuition tells me that it has something to do with the angular velocity. And then there's the fact that the target is mobile - I don't know if I should take that into account somehow or just ignore it. How do I calculate when the turret must "start braking"?

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  • tangent of two circles

    - by harryovers
    Hello, I am trying to write some code that that will draw the line which is a tangent between 2 circles. so far i have been able to draw multiple circles, and lines between the centers. i have a class which stores the values used in drawing the circles (radius, position). what i need is a method in this class to find all posible tangents between 2 circles. any help would be great. this is what i have so far (it could very well be a load of rubbish) public static Vector2[] Tangents(circle c1, circle c2) { if (c2.radius > c1.radius) { circle temp = c1; c1 = c2; c2 = temp; } circle c0 = new circle(c1.radius - c2.radius, c1.center); Vector2[] tans = new Vector2[2]; Vector2 dir = _point - _center; float len = (float)Math.Sqrt((dir.X * dir.X) + (dir.Y * dir.Y)); float angle = (float)Math.Atan2(dir.X, dir.Y); float tan_length = (float)Math.Sqrt((len * len) - (_radius * _radius)); float tan_angle = (float)Math.Asin(_radius / len); tans[0] = new Vector2((float)Math.Cos(angle + tan_angle), (float)Math.Sin(angle + tan_angle)); tans[1] = new Vector2((float)Math.Cos(angle - tan_angle), (float)Math.Sin(angle - tan_angle)); Vector2 dir0 = c0.center - tans[0]; Vector2 dir1 = c0.center - tans[1]; Vector2 tan00 = Vector2.Add(Vector2.Multiply(tans[0], (float)c2.radius), c1.center); Vector2 tan01 = c2.center; Vector2 tan10 = Vector2.Add(Vector2.Multiply(tans[1], (float)c2.radius), c1.center); Vector2 tan11 = c2.center; }

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  • How to rotate 3D axis(XYZ) using Yaw,Pitch,Roll angles in Opengl

    - by user3639338
    I am working Pose estimation with capturing from camera with Opencv. Now I had three angle(Yaw,Pitch,Roll) from each frame(Head) using my code.How to rotate 3D axis(XYZ) those three angle using opengl ? I draw 3D axis using opengl. I have Problem with rotate this axis for returning each frame(Head) using VideoCapture camera input from my code.I cant rotate continuously using returning three angle my code.

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  • slowly rotate an object towards another object

    - by numerical25
    I have an object that points in the direction of another object (i.e. it rotates to the direction that the second objects x and y coordinates are at) below is the code I use. var distx = target.x - x; var disty = target.y - y; var angle:Number = Math.atan2(disty, distx); var vx:Number = Math.cos(angle) * cspeed; var vy:Number = Math.sin(angle) * cspeed; rotation = angle * 180/Math.PI; x += vx; y += vy; as you can see. Not only does it rotate towards the target object, but it also moves towards it too. When I play the movie, the object instantly points to the targeted object and moves towards it. I would like for it to slowly turn towards the object instead of instantly turning towards it. anyone know how to do this.

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  • Is a line formed by two points greater than 90 degrees off of the horzontal.

    - by Scott Chamberlain
    I am trying to find out if a line defined by two points is greater than or equal to 90 degrees compared to the horizontal. Here is the code I used bool moreThan90 = false; double angle = Math.Atan((double)(EndingLocation.Y - Location.Y) / (double)(EndingLocation.X - Location.X)); if (angle >= Math.PI / 2.0 || angle <= -Math.PI / 2.0) moreThan90 = true; Did I do this correctly or is there a better built in function in .Net that will find this?

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  • Manually setting object's position or have the object do it all?

    - by N. Lucas
    I'm stuck thinking about the best way to go about setting a line segment's position, I have a class Line(length, angle, previous) being called from a class Polygon.. Right now I have: public function Line(length:Number, angle:Number, previous:Line = null) { if (previous != null) { this.x = previous.end.x; this.y = previous.end.y; } /**/ } Now, is this the best practice or should I be doing: Polygon.addLine(length:Number, angle:Number):void { var previous = _line[_line.length - 1]; // Array containing all Lines var line:Line = new Line(length, angle, previous); line.x = previous.end.x; line.y = previous.end.y; /**/ }

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  • c++ problem, maybe with types...

    - by Infinity
    Hi guys! I have a little problem in my code. The variables don't want to change their values. Can you say why? Here is my code: vector<coordinate> rocks(N); double angle; double x, y; // other code while (x > 1.0 || x < -1.0 || y > 1.0 || y < -1.0) { angle = rand() * 2.0 * M_PI; cout << angle << endl; cout << rocks[i - 1].x << endl; cout << rocks[i - 1].y << endl; x = rocks[i-1].x + r0 * cos(angle); y = rocks[i-1].y + r0 * sin(angle); cout << x << endl; cout << y << endl << endl; } // other code And the result on the console is: 6.65627e+09 0.99347 0.984713 1.09347 0.984713 1.16964e+09 0.99347 0.984713 1.09347 0.984713 As you see the values of x, y variables doesn't change and this while be an infinity loop. What's the problem? What do you think?

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  • Bullet physics in python and pygame

    - by Pomg
    I am programming a 2D sidescroller in python and pygame and am having trouble making a bullet go farther than just farther than the player. The bullet travels straight to the ground after i fire it. How, in python code using pygame do I make the bullet go farther. If you need code, here is the method that handles the bullet firing: self.xv += math.sin(math.radians(self.angle)) * self.attrs['speed'] self.yv += math.cos(math.radians(self.angle)) * self.attrs['speed'] self.rect.left += self.xv self.rect.top += self.yv

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  • How To Approach 360 Degree Snake

    - by Austin Brunkhorst
    I've recently gotten into XNA and must say I love it. As sort of a hello world game I decided to create the classic game "Snake". The 90 degree version was very simple and easy to implement. But as I try to make a version of it that allows 360 degree rotation using left and right arrows, I've come into sort of a problem. What i'm doing now stems from the 90 degree version: Iterating through each snake body part beginning at the tail, and ending right before the head. This works great when moving every 100 milliseconds. The problem with this is that it makes for a choppy style of gameplay as technically the game progresses at only 6 fps rather than it's potential 60. I would like to move the snake every game loop. But unfortunately because the snake moves at the rate of it's head's size it goes way too fast. This would mean that the head would need to move at a much smaller increment such as (2, 2) in it's direction rather than what I have now (32, 32). Because I've been working on this game off and on for a couple of weeks while managing school I think that I've been thinking too hard on how to accomplish this. It's probably a simple solution, i'm just not catching it. Here's some pseudo code for what I've tried based off of what makes sense to me. I can't really think of another way to do it. for(int i = SnakeLength - 1; i > 0; i--){ current = SnakePart[i], next = SnakePart[i - 1]; current.x = next.x - (current.width * cos(next.angle)); current.y = next.y - (current.height * sin(next.angle)); current.angle = next.angle; } SnakeHead.x += cos(SnakeAngle) * SnakeSpeed; SnakeHead.y += sin(SnakeAngle) * SnakeSpeed; This produces something like this: Code in Action. As you can see each part always stays behind the head and doesn't make a "Trail" effect. A perfect example of what i'm going for can be found here: Data Worm. Not the viewport rotation but the trailing effect of the triangles. Thanks for any help!

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  • How to sync the actions in a mutiplayer game?

    - by Wheeler
    I connect the clients with UDP (its a peer to peer connection on a multicast network) and the clients are sending their positions in every frame (in WP7 it means the default 30 FPS) to each other. This game is kinda a pong game, and my problem is the next: whenever the opponent hits the ball the angle will not be the same on both mobiles. I think its because the latency (1 pixel difference can cause a different angle). So my question is: how can I sync the hitting event?

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