Search Results

Search found 19338 results on 774 pages for 'game loop'.

Page 384/774 | < Previous Page | 380 381 382 383 384 385 386 387 388 389 390 391  | Next Page >

• How does this circle collision detection math work?

  - by Griffin

  I'm going through the wildbunny blog to learn about collision detection. I'm confused about how the vectors he's talking about come into play. Here's the part that confuses me: p = ||A-B|| – (r1+r2) The two spheres are penetrating by distance p. We would also like the penetration vector so that we can correct the penetration once we discover it. This is the vector that moves both circles to the point where they just touch, correcting the penetration. Importantly it is not only just a vector that does this, it is the only vector which corrects the penetration by moving the minimum amount. This is important because we only want to correct the error, not introduce more by moving too much when we correct, or too little. N = (A-B) / ||A-B|| P = N*p Here we have calculated the normalised vector N between the two centres and the penetration vector P by multiplying our unit direction by the penetration distance. I understand that p is the distance by which the circles penetrate, but I don't get what exactly N and P are. It seems to me N is just the coordinates of the 3rd point of the right trianlge formed by point A and B (A-B) then being divided by the hypotenuse of that triangle or distance between A and B (||A-B||). What's the significance of this? Also, what is the penetration vector used for? It seems to me like a movement that one of the circles would perform to get un-penetrated.

  Read the article

• OpenGL Application displays only 1 frame

  - by Avi

  EDIT: I have verified that the problem is not the VBO class or the vertex array class, but rather something else. I have a problem where my vertex buffer class works the first time its called, but displays nothing any other time its called. I don't know why this is, and it's also the same in my vertex array class. I'm calling the functions in this order to set up the buffers: enable client states bind buffers set buffer / array data unbind buffers disable client states Then in the draw function, that's called every frame: enable client states bind buffers set pointers unbind buffers bind index buffer draw elements unbind index buffer disable client states Is there something wrong with the order in which I'm calling the functions, or is it a more specific code error? EDIT: here's some of the code Code for setting pointers: //element is the vertex attribute being drawn (e.g. normals, colors, etc.) static void makeElementPointer(VertexBufferElements::VBOElement element, Shader *shade, void *elementLocation) { //elementLocation is BUFFER_OFFSET(n) if a buffer is bound switch (element) { .... glVertexPointer(3, GL_FLOAT, 0, elementLocation); //changes based on element .... //but I'm only dealing with } //vertices for now } And that's basically all the code that isn't just a straight OpenGL function call.

  Read the article

• Building dynamic bounding box hierachies.

  - by adivasile

  I've been reading about collision detection and I saw that the first part was a coarse detection which generates possible contacts using bounding box hierarchies. I understand the concept of splitting up your objects in groups, to speed up the detection phase, but I'm a little confused on how do you actually build the hierachy, more so on what criteria is used to group them together. Do I iterate through all the objects in the scene, and check the distance between them to see where they should be inserted in the tree? Do you know some resources that may shed some light on this topic for me?

  Read the article

• Need a good quality bitmap rotation algorithm for Android

  - by Lumis

  I am creating a kaleidoscopic effect on an android tablet. I am using the code below to rotate a slice of an image, but as you can see in the image when rotating a bitmap 60 degrees it distorts it quite a lot (red rectangles) – it is smudging the image! I have set dither and anti-alias flags but it does not help much. I think it is just not a very sophisticated bitmap rotation algorithm. canvas.save(); canvas.rotate(angle, screenW/2, screenH/2); canvas.drawBitmap(picSlice, screenW/2, screenH/2, pOutput); canvas.restore(); So I wonder if you can help me find a better way to rotate a bitmap. It does not have to be fast, because I intend to use a high quality rotation only when I want to save the screen to the SD card - I would redraw the screen in memory before saving. Do you know any comprehensible or replicable algorithm for bitmap rotation that I could programme or use as a library? Or any other suggestion? EDIT: The answers below made me think if Android OS had bilinear or bicubic interpolation option and after some search I found that it does have its own version of it called FilterBitmap. After applying it to my paint pOutput.setFilterBitmap(true); I get much better result

  Read the article

• BOX2D Kinematic Platform with parallax layer

  - by Marcell

  I am using a kinematic body for my moving platform on x-axis, so I set the linear velocity to b2vec2(5,0). When the player jump on the platform, it works like it is suppose to. But the thing is that my platform is on the obstacle layer and I am moving it with the parallax layer. So if I setTransform the kinematic platform to follow the obstacle layer than it's physics will not work and the player will slip-off the platform. I'm developing for iOS and using cocos2d api. Anyway around this?

  Read the article

• Collision 2D Quads

  - by Vico Pelaez

  I want to detect collision between two 2D squares, one square is static and the other one moves according to keyboard arrows. I have implemented some code, however nothing happens when they overlap each other and what I tried to achieve in the code was to detect an overlapping between them. I think I am either not understanding the concept really well or that because one of the squares is moving this is not working. Please I would really appreciate your help. Thank you! float x1=0.05 ,Y1=0.05; float x2=0.05 ,Y2=0.05; float posX1 =0.5, posY1 = 0.5; float movX2 = 0.0 , movY2 = 0.0; struct box{ int width=0.1; int heigth=0.1; }; void init(){ glClearColor(0.0, 0.0, 0.0, 0.0); glColor3f(1.0, 1.0, 1.0); } void quad1(){ glTranslatef(posX1, posY1, 0.0); glBegin(GL_POLYGON); glColor3f(0.5, 1.0, 0.5); glVertex2f(-x1, -Y1); glVertex2f(-x1, Y1); glVertex2f(x1,Y1); glVertex2f(x1,-Y1); glEnd(); } void quad2(){ glMatrixMode(GL_PROJECTION); glLoadIdentity(); glPushMatrix(); glTranslatef(movX2, movY2, 0.0); glBegin(GL_POLYGON); glColor3f(1.5, 1.0, 0.5); glVertex2f(-x2, -Y2); glVertex2f(-x2, Y2); glVertex2f(x2,Y2); glVertex2f(x2,-Y2); glEnd(); glPopMatrix(); } void reset(){ //Reset position of square??? movX2 = 0.0; movY2 = 0.0; collisionB = false; } bool collision(box A, box B){ int leftA, leftB; int rightA, rightB; int topA, topB; int bottomA, bottomB; //Calculate the sides of box A leftA = x1; rightA = x1 + A.width; topA = Y1; bottomA = Y1 + A.heigth; //Calculate the sides of box B leftB = x2; rightB = x2 + B.width; topB = Y1; bottomB = Y1+ B.heigth ; if( bottomA <= topB ) return false; if( topA >= bottomB ) return false; if( rightA <= leftB ) return false; if( leftA >= rightB ) return false; return true; } float move_unit = 0.1; void keyboardown(int key, int x, int y) { switch (key){ case GLUT_KEY_UP: movY2 += move_unit; break; case GLUT_KEY_RIGHT: movX2 += move_unit; break; case GLUT_KEY_LEFT: movX2 -= move_unit; break; case GLUT_KEY_DOWN: movY2 -= move_unit; break; default: break; } glutPostRedisplay(); } void display(){ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_PROJECTION); glLoadIdentity(); cuad1(); if (!collision) { cuad2(); } else{ reset(); } glFlush(); } int main(int argc, char** argv){ glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(500,500); glutInitWindowPosition(0, 0); glutCreateWindow("Collision Practice"); glutSpecialFunc(keyboardown); glutDisplayFunc(display); init(); glutMainLoop(); }

  Read the article

• Unity mouse input not working in webplayer build

  - by Califer

  I have a button script with the following code void OnMouseDown() { animation.Play("button-squish"); enlarged = true; audio.PlayOneShot(buttonSound); } void OnMouseUpAsButton() { if (enlarged) { SelectThisButton(); enlarged = false; animation.Play("button-return"); } } void OnMouseExit() { if (enlarged) { enlarged = false; animation.Play("button-return"); } } It works great in the editor, but when I made a build and tested it in Chrome none of the buttons had any response. Further testing revealed that it did work in Firefox. Rather than telling people to change their browser if they want to play, I want to make the button code work. How else can I get the buttons to know when they're being pressed if the built-in stuff isn't working?

  Read the article

• How to obtain window handle in SDL 2.0.3

  - by Diorthotis

  I need to obtain the handle of the window for SDL 2.0.3. I got the suggestion to use info.window after initializing SDL and filling the info variable with data by calling SDL_GetWindowWMInfo(); included in the header file SDL_syswm.h. My compiler (visual studio 2008 professional edition) gives the following error: 226) : error C2039: 'window' : is not a member of 'SDL_SysWMinfo' 1 include\sdl_syswm.h(173) : see declaration of 'SDL_SysWMinfo' Any help appreciated. Thanks. Nevermind, I needed to use "info.info.win.window". That seems a bit redundant, but whateves.

  Read the article

• How do I use unpackHalf2x16?

  - by user1032861

  I'm trying to use (un)packHalf2x16, without success so far. I'm drawing with: glVertexAttribIPointer(0, 2, GL_UNSIGNED_INT, 0, 0); glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vbo); glDrawArrays(GL_POINTS, 0, n_points); glDisableVertexAttribArray(0); and on the shader #version 330 core #extension GL_ARB_shading_language_packing : require in uvec2 A0; // (...) vec4 t = vec4(unpackHalf2x16(A0.x), unpackHalf2x16(A0.y)); But nothing gets drawn. I'm pretty sure buffer's content is right, and if I use vec4 t = vec4(0); I can see it's working properly. How is this packing / unpacking thing supposed to work? I can't find any example.

  Read the article

• Simple 2D Flight Physics with Box2D

  - by MarkPowell

  I'm trying to build a simple side scroller with an airplane being the player. As such, I want to build simple flight controls with simple but realistic-feeling physics. I'm making use of cocos2D and Box2D. I have a basic system working, but just can't get the physics feeling correct. I am applying force to the plane (which is a b2CircleShape) based on the user's input. So, basically, if the user pushes up, body_->ApplyForce(b2Vec2(10,30), body_->GetPosition()) is called. Similarly, for down -30 is used. This works and the plane flys along with up/down causing it to dive or climb. But it just doesn't feel right. There is no slowdown on climbs, nor speed up during dives. My simple solution is far to simple. How can I get a better feel for a plane climbing/diving? Thanks!

  Read the article

• D3DXMatrixDecompose gives different quaternion than D3DXQuaternionRotationMatrix

  - by Fraser

  In trying to solve this problem, I tracked down the problem to the conversion of the rotation matrix to quaternion. In particular, consider the following matrix: -0.02099178 0.9997436 -0.008475631 0 0.995325 0.02009799 -0.09446743 0 0.09427284 0.01041905 0.9954919 0 0 0 0 1 SlimDX.Quaternion.RotationMatrix (which calls D3DXQuaternionRotationMatrix gives a different answer than SlimDX.Matrix.Decompose (which uses D3DXMatrixDecompose). The answers they give (after being normalized) are: X Y Z W Quaternion.RotationMatrix -0.05244324 0.05137424 0.002209336 0.9972991 Matrix.Decompose 0.6989997 0.7135442 -0.03674842 -0.03006023 Which are totally different (note the signs of X, Z, and W are different). Note that these aren't q/-q (two quaternions that represent the same rotation); they face completely different directions. I've noticed that with matrices for rotations very close to that one (successive frames in the animation) that the Matrix.Decompose version gives a solution that flips around wildly and occasionally goes into the desired position, while the Quaternion.RotationMatrix version gives solutions that are stable but go in the wrong direction. This is only for the right arm in my animation -- for the left arm, both functions give the correct solution, which is the same quaternion within error tolerances. This makes me think that there's some sort of numeric instability or weird stuff with signs going on. I tried implementing this and then this, but both gave me a completely incorrect solution (even for the matricies where the SlimDX ones were working correctly) -- maybe the rows and columns are flipped?

  Read the article

• Why doesn't light continuous on my model?

  - by nosferat

  I created a basic textured cube model with Blender to practice modeling, and then I imported it into Unity. After I put up some lighting it looks pretty ugly. The light is not continuous on a row of textured cubes: What is more odd, the light on the blocks that makes up the floor is continuous. What am I doing wrong? UPDATE This is how it looks like without textures: https://dl.dropbox.com/u/45620018/without%20textures.PNG If I would not know that these are perfect cubes, I'd say there is a slight curve on surface. I also tried lightening the texture but it also didn't help: https://dl.dropbox.com/u/45620018/lighter%20texture.PNG I just simply exported the model from Blender and did not set up any normals or things like that. However I also did not do any special woth the floor brick model.

  Read the article

• Edge flicker when moving Camera (2D)

  - by Matthias Reisner

  I have a Orthographic camera. I have a fixed landscape texture and a texture for a moveable object. If the object moves to the right the camera will also move with the object. When I also draw an score text that should have fixed position on the screen, that score text position will be update too if the camera's position gets updated so that it looks like that it is fixed on the screen. But if I do that, I have some edge flickering at the text object. I'am using SpriteBatch! Is there another approach to implement a fixed positioned object on the screen?

  Read the article

• OpenGL ES multiple objects not being rendered

  - by ladiesMan217

  I am doing the following to render multiple balls move around the screen but only 1 ball is seen to appear and function. I don't know why the rest (count-1) balls are not being drawn public void onDrawFrame(GL10 gl) { // TODO Auto-generated method stub gl.glDisable(GL10.GL_DITHER); gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glClientActiveTexture(DRAWING_CACHE_QUALITY_HIGH); gl.glLoadIdentity(); for(int i=0;i<mParticleSystem.getParticleCount();i++){ gl.glPushMatrix(); gl.glTranslatef(mParticleSystem.getPosX(i), mParticleSystem.getPosY(i), -3.0f); gl.glScalef(0.3f, 0.3f, 0.3f); gl.glColor4f(r.nextFloat(), r.nextFloat(), r.nextFloat(), 1); gl.glEnable(GL10.GL_TEXTURE_2D); mParticleSystem.getBall(i).draw(gl); gl.glPopMatrix(); } } Here is my void draw(GL10 gl) method public void draw(GL10 gl){ gl.glEnable(GL10.GL_CULL_FACE); gl.glEnable(GL10.GL_SMOOTH); gl.glEnable(GL10.GL_DEPTH_TEST); // gl.glTranslatef(0.2f, 0.2f, -3.0f); // gl.glScalef(size, size, 1.0f); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertBuff); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, 0, points/2); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); }

  Read the article

• Camera placement sphere for an always fully visible object

  - by BengtR

  Given an object: With the bounds [x, y, z, width, height, depth] And an orthographic projection [left, right, bottom, top, near, far] I want to determine the radius of a sphere which allows me to randomly place my camera on so that: The object is fully visible from all positions on this sphere The sphere radius is the smallest possible value while still satisfying 1. Assume the object is centered around the origin. How can I find this radius? I'm currently using sqrt(width^2 + height^2 + depth^2) but I'm not sure that's the correct value, as it doesn't take the camera into account. Thanks for any advice. I'm sorry for confusing a few things here. My comments below should clarify what I'm trying to do actually.

  Read the article

• Black or White Border/Shadow around PNGs in SDL/OPENGL

  - by Dylan

  having the same issue as this: Why do my sprites have a dark shadow/line/frame surrounding the texture? however, when I do the fix suggested there (changing GL_SRC_ALPHA to GL_ONE) it just replaces the black border with a white border on the images, and messes with my background color and some polygons I'm drawing (not all of them weirdly) by making them much lighter... any ideas? heres some of my relevant code. init: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glEnable(GL_DEPTH_TEST); glEnable(GL_MULTISAMPLE); glEnable(GL_TEXTURE_2D); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glAlphaFunc(GL_GREATER, 0.01); glEnable(GL_ALPHA_TEST); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glEnable(GL_BLEND); when each texture is loaded: glGenTextures(1, &textureID); glBindTexture(GL_TEXTURE_2D, textureID); gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, surface->w, surface->h, GL_BGRA, GL_UNSIGNED_BYTE, surface->pixels); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  Read the article

• InputLayout handling

  - by Kikaimaru

  Where are you supposed to store InputLayout? Suppose i have some basic structure like. class Mesh { List<MeshPart> MeshParts } class MeshPart { Effect Effect; VertexBufferBinding VertexBuffer; ... } Where should I store input layout? It's a connection between vertex buffer and specific pass, i can live with just 1 pass but I still have diffferent techniques so i need at least an array with some connection to effecttechniques, but I would appriciate something not crazy like dictionary. I could also create wrapper for Effect and EffectTechnique, but there must be some normal solution.

  Read the article

• Checking for collisions on a 3D heightmap

  - by Piku

  I have a 3D heightmap drawn using OpenGL (which isn't important). It's represented by a 2D array of height data. To draw this I go through the array using each point as a vertex. Three vertices are wound together to form a triangle, two triangles to make a quad. To stop the whole mesh being tiny I scale this by a certain amount called 'gridsize'. This produces a fairly nice and lumpy, angular terrain kind of similar to something you'd see in old Atari/Amiga or DOS '3D' games (think Virus/Zarch on the Atari ST). I'm now trying to work out how to do collision with the terrain, testing to see if the player is about to collide with a piece of scenery sticking upwards or fall into a hole. At the moment I am simply dividing the player's co-ordinates by the gridsize to find which vertex the player is on top of and it works well when the player is exactly over the corner of a triangle piece of terrain. However... How can I make it more accurate for the bits between the vertices? I get confused since they don't exist in my heightmap data, they're a product of the GPU trying to draw a triangle between three points. I can calculate the height of the point closest to the player, but not the space between them. I.e if the player is hovering over the centre of one of these 'quads', rather than over the corner vertex of one, how do I work out the height of the terrain below them? Later on I may want the player to slide down the slopes in the terrain.

  Read the article

• Avoiding orbiting in pursuit steering behavior

  - by bobobobo

  I have a missile that does pursuit behavior to track (and try and impact) its (stationary) target. It works fine as long as you are not strafing when you launch the missile. If you are strafing, the missile tends to orbit its target. I fixed this by accelerating tangentially to the target first, killing the tangential component of the velocity first, then beelining for the target. So I accelerate in -vT until vT is nearly 0. Then accelerate in the direction of vN. While that works, I'm looking for a more elegant solution where the missile is able to impact the target without explicitly killing the tangential component first.

  Read the article

• Binding BoundingSpheres to a world matrix in XNA

  - by NDraskovic

  I made a program that loads the locations of items on the scene from a file like this: using (StreamReader sr = new StreamReader(OpenFileDialog1.FileName)) { String line; while ((line = sr.ReadLine()) != null) { red = line.Split(','); model = row[0]; x = row[1]; y = row[2]; z = row[3]; elements.Add(Convert.ToInt32(model)); data.Add(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z))); sfepheres.Add(new BoundingSphere(new Vector3(Convert.ToSingle(x), Convert.ToSingle(y), Convert.ToSingle(z)), 1f)); } I also have a list of BoundingSpheres (called spheres) that adds a new bounding sphere for each line from the file. In this program I have one item (a simple box) that moves (it has its world matrix called matrixBox), and other items are static entire time (there is a world matrix that holds those elements called simply world). The problem i that when I move the box, bounding spheres move with it. So how can I bind all BoundingSpheres (except the one corresponding to the box) to the static world matrix so that they stay in their place when the box moves?

  Read the article

• View space lighting in deferred shading

  - by kochol

  I implemented a simple deferred shading renderer. I use 3 G-Buffer for storing position (R32F), normal (G16R16F) and albedo (ARGB8). I use sphere map algorithm to store normals in world space. Currently I use inverse of view * projection matrix to calculate the position of each pixel from stored depth value. First I want to avoid per pixel matrix multiplication for calculating the position. Is there another way to store and calculate position in G-Buffer without the need of matrix multiplication Store the normal in view space Every lighting in my engine is in world space and I want do the lighting in view space to speed up my lighting pass. I want an optimized lighting pass for my deferred engine.

  Read the article

• OpenGL render to texture causing edge artifacts

  - by mysticalOso

  This is my first post here so any help would be massively appreciated :) I'm using C++ with SDL and OpenGL 3.3 When rendering directly to screen I get the following result And when I render to texture I this happens Anti-aliasing is turned off for both. I'm guessing this has something to do with depth buffer accuracy but I've tried a lot of different methods to improve the result but, no success :( I'm currently using the following code to set up my FBO: GLuint frameBufferID; glGenFramebuffers(1, &frameBufferID); glBindFramebuffer(GL_FRAMEBUFFER, frameBufferID); glGenTextures(1, &coloursTextureID); glBindTexture(GL_TEXTURE_2D, coloursTextureID); glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,SCREEN_WIDTH,SCREEN_HEIGHT,0,GL_RGB,GL_UNSIGNED_BYTE,NULL); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); //Depth buffer setup GLuint depthrenderbuffer; glGenRenderbuffers(1, &depthrenderbuffer); glBindRenderbuffer(GL_RENDERBUFFER, depthrenderbuffer); glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, SCREEN_WIDTH,SCREEN_HEIGHT); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthrenderbuffer); glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, coloursTextureID, 0); GLenum DrawBuffers[1] = {GL_COLOR_ATTACHMENT0}; glDrawBuffers(1, DrawBuffers); // if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) return false; Thank you so much for any help :)

  Read the article

• C++ Directx 11 D3DXVECTOR3 doesn't allow me to devide it

  - by Miguel P

  If i have a simple vector3 like this: D3DXVECTOR3 inversevector = D3DXVECTOR3( (pos+lookat_pos)); It works perfect! But let's say i wanted to multiply it by: Speed*(float) timeHandler.GetDelta() So: D3DXVECTOR3 inversevector = D3DXVECTOR3( (pos+lookat_pos) * Speed*(float) timeHandler.GetDelta()); Now this fails completely, i've used this snippet before, but for some wierd reason it simply won't work( The vector somehow leads x,y,z to 0 or almost, no idea why). Do you have any idea why?

  Read the article

• glTranslate, how exactly does it work?

  - by mykk

  I have some trouble understanding how does glTranslate work. At first I thought it would just simply add values to axis to do the transformation. However then I have created two objects that would load bitmaps, one has matrix set to GL_TEXTURE: public class Background { float[] vertices = new float[] { 0f, -1f, 0.0f, 4f, -1f, 0.0f, 0f, 1f, 0.0f, 4f, 1f, 0.0f }; .... private float backgroundScrolled = 0; public void scrollBackground(GL10 gl) { gl.glLoadIdentity(); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glTranslatef(0f, 0f, 0f); gl.glPushMatrix(); gl.glLoadIdentity(); gl.glMatrixMode(GL10.GL_TEXTURE); gl.glTranslatef(backgroundScrolled, 0.0f, 0.0f); gl.glPushMatrix(); this.draw(gl); gl.glPopMatrix(); backgroundScrolled += 0.01f; gl.glLoadIdentity(); } } and another to GL_MODELVIEW: public class Box { float[] vertices = new float[] { 0.5f, 0f, 0.0f, 1f, 0f, 0.0f, 0.5f, 0.5f, 0.0f, 1f, 0.5f, 0.0f }; .... private float boxScrolled = 0; public void scrollBackground(GL10 gl) { gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glTranslatef(0f, 0f, 0f); gl.glPushMatrix(); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glTranslatef(boxScrolled, 0.0f, 0.0f); gl.glPushMatrix(); this.draw(gl); gl.glPopMatrix(); boxScrolled+= 0.01f; gl.glLoadIdentity(); } } Now they are both drawn in Renderer.OnDraw. However background moves exactly 5 times faster. If I multiply boxScrolled by 5 they will be in sinc and will move together. If I modify backgrounds vertices to be float[] vertices = new float[] { 1f, -1f, 0.0f, 0f, -1f, 0.0f, 1f, 1f, 0.0f, 0f, 1f, 0.0f }; It will also be in sinc with the box. So, what is going under glTranslate?

  Read the article

• What is going on in this SAT/vector projection code?

  - by ssb

  I'm looking at the example XNA SAT collision code presented here: http://www.xnadevelopment.com/tutorials/rotatedrectanglecollisions/rotatedrectanglecollisions.shtml See the following code: private int GenerateScalar(Vector2 theRectangleCorner, Vector2 theAxis) { //Using the formula for Vector projection. Take the corner being passed in //and project it onto the given Axis float aNumerator = (theRectangleCorner.X * theAxis.X) + (theRectangleCorner.Y * theAxis.Y); float aDenominator = (theAxis.X * theAxis.X) + (theAxis.Y * theAxis.Y); float aDivisionResult = aNumerator / aDenominator; Vector2 aCornerProjected = new Vector2(aDivisionResult * theAxis.X, aDivisionResult * theAxis.Y); //Now that we have our projected Vector, calculate a scalar of that projection //that can be used to more easily do comparisons float aScalar = (theAxis.X * aCornerProjected.X) + (theAxis.Y * aCornerProjected.Y); return (int)aScalar; } I think the problems I'm having with this come mostly from translating physics concepts into data structures. For example, earlier in the code there is a calculation of the axes to be used, and these are stored as Vector2, and they are found by subtracting one point from another, however these points are also stored as Vector2s. So are the axes being stored as slopes in a single Vector2? Next, what exactly does the Vector2 produced by the vector projection code represent? That is, I know it represents the projected vector, but as it pertains to a Vector2, what does this represent? A point on a line? Finally, what does the scalar at the end actually represent? It's fine to tell me that you're getting a scalar value of the projected vector, but none of the information I can find online seems to tell me about a scalar of a vector as it's used in this context. I don't see angles or magnitudes with these vectors so I'm a little disoriented when it comes to thinking in terms of physics. If this final scalar calculation is just a dot product, how is that directly applicable to SAT from here on? Is this what I use to calculate maximum/minimum values for overlap? I guess I'm just having trouble figuring out exactly what the dot product is representing in this particular context. Clearly I'm not quite up to date on my elementary physics, but any explanations would be greatly appreciated.

  Read the article

< Previous Page | 380 381 382 383 384 385 386 387 388 389 390 391  | Next Page >