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  • Pygame surface rotation, rect rotation or sprite rotation?

    - by Alan
    i seem to have a conceptual misunderstanding of the surface and rect object in pygame. I currently observe these objects this way: Surface Just the loaded image rect the 'hard' representation of the ingame object (sprite). Used for simplifying object moment and collision detection sprite rect and surface grouped together What i want to do is rotate my sprite. The only available method i found for rotation is pygame.transform.rotate. How do i rotate the rectangle, or even better, the whole sprite? Below is the image of how i visualize this problem.

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  • Finetuning movement based on gradual rotation towards a target

    - by A.B.
    I have an object which moves towards a target destination by gradually adjusting its facing while moving forwards. If the target destination is in a "blind spot", then the object is incapable of reaching it. This problem is ilustrated in the picture below. When the arrow is ordered to move to point A, it will only end up circling around it (following the red circle) because it is not able to adjust its rotation quickly enough. I'm interested in a solution where the movement speed is multiplied by a number from 0.1 to 1 in proportion to necessity. The problem is, how do I calculate whether it is necessary in the first place? How do I calculate an appropriate multiplier that is neither too small nor too large? void moveToPoint(sf::Vector2f destination) { if (destination == position) return; auto movement_distance = distanceBetweenPoints(position, destination); desired_rotation = angleBetweenPoints(position, destination); /// Check whether rotation should be adjusted if (rotation != desired_rotation) { /// Check whether the object can achieve the desired rotation within the next adjustment of its rotation if (Radian::isWithinDistance(rotation, desired_rotation, rotation_speed)) { rotation = desired_rotation; } else { /// Determine whether to increment or decrement rotation in order to achieve desired rotation if (Radian::convert(desired_rotation - rotation) > 0) { /// Increment rotation rotation += rotation_speed; } else { /// Decrement rotation rotation -= rotation_speed; } } } if (movement_distance < movement_speed) { position = destination; } else { position.x = position.x + movement_speed*cos(rotation); position.y = position.y + movement_speed*sin(rotation); } updateGraphics(); }

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  • Need to translate a Rotation Matrix to Rotation y, x, z OpenGL & Jitter for 3D Game

    - by MineMan287
    I am using the Jitter Physics engine which gives a rotation matrix: M11 M12 M13 M21 M22 M23 M21 M32 M33 And I need it so OpenGL can use it for rotation GL.Rotate(xr, 1, 0, 0) GL.Rotate(yr, 0, 1, 0) GL.Rotate(zr, 0, 0, 1) Initially I Tried xr = M11 yr = M22 zr = M33 [1 0 0] [0 1 0] [0 0 1] Which did not work, please help, I have been struggling on this for days :( Re-Edit The blocks are stored in text files with Euler angles so it needs to be converted or the rendering engine will simply fail. I am now using the matrix in the text files. Example Block 1,1,1 'Size 0,0,0 'Position 255,255,255 'Colour 0,0,0,0,0,0,0,0,0 'Rotation Matrix

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  • Weird rotation problem

    - by Phil
    I'm creating a simple tank game. No matter what I do, the turret keeps facing the target with it's side. I just can't figure out how to turn it 90 degrees in Y once so it faces it correctly. I've checked the pivot in Maya and it doesn't matter how I change it. This is the code I use to calculate how to face the target: void LookAt() { var forwardA = transform.forward; var forwardB = (toLookAt.transform.position - transform.position); var angleA = Mathf.Atan2(forwardA.x, forwardA.z) * Mathf.Rad2Deg; var angleB = Mathf.Atan2(forwardB.x, forwardB.z) * Mathf.Rad2Deg; var angleDiff = Mathf.DeltaAngle(angleA, angleB); //print(angleDiff.ToString()); if (angleDiff > 20) { //Rotate to transform.Rotate(new Vector3(0, (-turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else if (angleDiff < 20) { transform.Rotate(new Vector3(0, (turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else { } } I'm using Unity3d and would appreciate any help I can get! Thanks!

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  • XNA - 2D Rotation of an object to a selected direction

    - by lobsterhat
    I'm trying to figure out the best way of rotating an object towards the directional input of the user. I'm attempting to mimic making turns on ice skates. For instance, if the player is moving right and the input is down and left, the player should start rotating to the right a set amount each tick. I'll calculate a new vector based on current velocity and rotation and apply that to the current velocity. That should give me nice arcing turns, correct? At the moment I've got eight if/else statements for each key combination which in turn check the current rotation: // Rotate to 225 if (keyboardState.IsKeyDown(Keys.Up) && keyboardState.IsKeyDown(Keys.Left)) { // Rotate right if (rotation >= 45 || rotation < 225) { rotation += ROTATION_PER_TICK; } // Rotate left else if (rotation < 45 || rotation > 225) { rotation -= ROTATION_PER_TICK; } } This seems like a sloppy way to do this and eventually, I'll need to do this check about 10 times a tick. Any help toward a more efficient solution is appreciated.

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  • Converting 3 axis vectors to a rotation matrix

    - by user38858
    I am trying to get a rotation matrix (in 3dsmax) from 3 vectors that form an axis (all 3 vectors are aligned by 90 degrees each other) Somewhere I read that I could build a rotation matrix just by inserting in every row one vector at a time (source: http://renderdan.blogspot.cz/2006/05/rotation-matrix-from-axis-vectors.html) So, I built a matrix with these example vectors x-axis : [-0.194624,-0.23715,-0.951778] y-axis : [-0.773012,0.634392,0] z-axis : [-0.6038,-0.735735,0.306788] But for some reason, if I try to convert this matrix to eulerangles, I receive this rotation: (eulerAngles 47.7284 6.12831 36.8263) ... which is totally wrong, and doesn't align to my 3 vectors at all. I know that rotation is quite difficult to understand, may someone shed some light? :)

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  • CW/CCW Rotation of a Vector

    - by user23132
    Considering that I have a vector A, and after an arbitrary rotation I get vector B. I want to use this rotation operation in others vectors as well, but I'm having problems in doing that. My idea do that is to calculate the perpendicular vector C of the plane AB (by calculating AxB). This vector C is the axis that I'll need to rotate. To discover the angle I used the dot product between A and B, the acos of the dot product will return the lowest angle between A and B, the angle ang. The rotation I need to do is then: -rotate *ang*º around the C axis. The problem is that I dont know if this rotation is a CW or CCW rotation, since the cos of the dot product does not give me information of the sign of the angle. There's a tip discover that in 2D ( A.x * B.y - A.y * B.x) that you can use to discover if the vector A is at left/right of vector B. But I dont know how to do this in 3D space. Can anyone help me?

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  • Confusion about Rotation matrices from Euler Angles

    - by xEnOn
    I am trying to learn more about Euler Angles so as to help myself in understanding how I can control my camera better in the game. I came across the following formula that converts Euler Angles to rotation matrices: In the equation, I could see that the first matrix from the left is the rotation matrix about x-axis, the second is about y-axis and the third is about z-axis. From my understanding about ordinary matrix transformations, the later transformation is always applied to the right hand side. And if I'm right about this, then the above equation should have a rotation order starting from rotating about z-axis, y-axis, then finally x-axis. But, from the symbols it seems that the rotation order start rotating about x-axis, then y-axis, then finally z-axis. What should the actual order of the rotation be? Also, I am confuse about if the input vector, in this case, would be a row vector on the left, or a column vector on the right?

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  • Smoothing rotation

    - by Lewis
    I've spent the last three days trying to work out how to rotate a sprite smoothly depending on the velocity.x value of the sprite. I'm using this: float Proportion = 9.5; float maxDiff = 200; float rotation = fmaxf(fminf(playerVelocity.x * Proportion, maxDiff), -maxDiff); player.rotation = rotation; The behaviour is what I required but if the velocity changes rapidly then it will look like the sprite will jump to face left or jump to face right. I'll go into the behaviour in a little more detail: 0 velocity = sprite faces forwards negative velocity = sprite faces left depending on value. positive velocity = sprite faces right (higher velocity the more it faces right) same as above. I've read about using interpolation rather than an absolute angle to rotate it to but I don't know how to implement that. I have a physics engine available. There is one other way to get around this: to use += on the rotation angle. The thing is that I would then have to change the equation to produce positive and negative values then to make sure the sprite faces 0 once it reaches 0 velocity again. If I add that in now, it keeps the previous angle even after the velocity has dropped / is dropping. Any ideas/code snippets would be greatly appreciated.

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  • Slerping rotation mirrors

    - by Esa
    I rotate my game character to watch at the target using the following code: transform.rotation = Quaternion.Slerp(startQuaternion, lookQuaternion, turningNormalizer*turningSpeed/10f) startQuaternion is the character's current rotation when a new target is given. lookQuaternion is the direction the character should look at and it's set like this: destinationVector = currentWaypoint.transform.position - transform.position; lookQuaternion = Quaternion.LookRotation(destinationVector, Vector3.up); turningNormalizer is just Time.deltaTime incremented and turningSpeed is a static value given in the editor. The problem is that while the character turns as it should most of the time, it has problems when it has to do close to 180 degrees. Then it at times jitters and mirrors the rotation: In this poorly drawn image the character(on the right) starts to turn towards the circle on the left. Instead of just turning either through left or right it starts this "mirror dance": It starts to rotate towards the new facing Then it suddenly snaps to the same angle but on other side and keeps rotating It does this "mirroring" so long until it looks at the target. Is this a thing with quaternions, slerping/lerping or something else?

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  • Passing an objects rotation down through its children

    - by MintyAnt
    In my topdown 2d game you have a player with a sword, like an old Zelda game. The sword is a seperate entity, and its collision box "rotates" around the player like an orbit, but always follows the player wherever he goes. The player and sword both have a vector2 heading. The sword is a weapon object that is attached to the character. In order to allow swinging in a direction, I have the following property inside sword (RotateCopy returns a copy of the mHeading after rotation) public Vector2 Heading { get { return mHeading.RotateCopy(mOwner.Rotation); } } This seems a bit messy to me, and slower than it could be. Is there a better way to "translate" the base/owner component rotations through to whatever component I am using, like this sword? Would using a rotation MATRIX be better? (Curretnly rotates by sin/cos) If so, how can I "add" up the matrices? Thank you.

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  • Rotation, further I go from 0:0, the further the object positions around the origin while rotating

    - by Serguei Fedorov
    For some reason I am having the issue where the following code: global.spriteBatch.Draw(obj.sprite, obj.getPosition(), null, Color.White, obj.rotation, obj.center, 2f, SpriteEffects.None, 1); causes the object to rotate around the origin in such a way, as though there is an offset to the position relative to its location. The calculation for the center it correct and this happens even if I set the pivot to be the location of the object. The further I get from 0:0 the larger the radius or rotation. I am not sure what is going on here because given the following tutorial http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2D/Rotation.php I have done the code setup correctly. Any ideas? Any help is greatly appreciated!!!

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  • Tetris : Effective rotation

    - by hqt
    I rotate each piece by rotation formula. More detail, because rotation angle is 90 so : xNew = y; yNew = -x; But my method has met two problems : 1) Out of box : each type of pieces is fit in square 4x4. (0,0 at under left) But by this rotation, at some case they will out of this box. For example, there is a point with coordinate (5,6) So, please help me how to fit these coordinate into 4x4 box again, or give me another formula for this. 2) at I case : (4 squares at same row or same column), just has two rotations case. but in method above, they still has 4 pieces. So, how to prevent this. Thanks :)

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  • Matrix rotation wrong orientation LibGDX

    - by glz
    I'm having a problem with matrix rotation in libgdx. I rotate it using the method matrix.rotate(Vector3 axis, float angle) but the rotation happens in the model orientation and I need it happens in the world orientation. For example: on create() method: matrix.rotate(new Vector3(0,0,1), 45); That is ok, but after: on render() method: matrix.rotate(new Vector3(0,1,0), 1); I need it rotate in world axis.

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  • Projectile Rotation

    - by Alex
    I'm trying to add a projectile system like the projectiles in Realm Of The Mad God. (YouTube it to see what I mean) These projectiles seem to move according to their rotation perfectly and can have nearly any rotation. They also have near perfect hitboxing. What's the maths behind this? My Game works on an integer-based coordinate system, but at the moment projectiles can only shoot either 0, 45, 90, 135, 180, 225, 270 and 315 degrees.

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  • 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

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  • Box2D body rotation with setTransform

    - by thobens
    I' having a problem rotating a body with setTransform(), The body has multiple sensors that should rotate with the player. The rotation works but it rotates around the bodys local 0,0 position instead of the center. Note that the game is in a top-down perspective and the player can go in four different directions, thus I need to rotate him immediately (in one tick) in 90 degrees steps. Up: Down: I can't find a way to set the rotation center. Here's the code I use to rotate it: float angle = direction * 90 * MathUtils.degRad; // direction is an int value from 0 to 3 body.setTransform(body.getPosition(), angle); I also tried body.getLocalCenter().set() and bc.body.getMassData().center.set() but it didn't seem to have any effect. How can I rotate the body around its center?

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  • Calculate gears rotation for a realtime simulation

    - by nkint
    Hi I'm trying to do a game with real time simulations of gears. There is a big Gear with inside a smaller gear. I managed to draw gears with different diameters but equal size teeth, but if i try to move the smaller one inside the bigger one the movement is odd. see the animated gif. the biggest gear is in center C1 and the small in the center C2. I calculate C2 position in this way: C2.x = C1.x + C1_RADIUS-C2_RADIUS) * cos(t); C2.y = C1.y - C1_RADIUS-C2_RADIUS) * sin(t); for t that goes from 0 to TWO_PI in n steps. I apply as rotation the angle t, but maybe it is wrong and i have to calculate another rotation for get a perfect joint

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  • Rotation matrix for a 3D vector

    - by Shashwat
    I have a direction vector on which I have to apply some rotation to align it to positive z-axis. To use Matrix.CreateRotationX(angle) of XNA, I need the angle for which I'd have to compute cos or tan inverse. I think this is a complex task to do. Also, eventually those are also converted to sin(angle) and cos(angle) in the matrix. Is there any inbuilt way to create rotation matrix from a 3D vector? However, I can write the function but still asking if there is one already there.

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  • 2d movement solution

    - by Phil
    Hi! I'm making a simple top-down tank game on the ipad where the user controls the movement of the tank with the left "joystick" and the rotation of the turret with the right one. I've spent several hours just trying to get it to work decently but now I turn to the pros :) I have two referencial objects, one for the movement and one for the rotation. The referencial objects always stay max two units away from the tank and I use them to tell the tank in what direction to move. I chose this approach to decouple movement and rotational behaviour from the raw input of the joysticks, I believe this will make it simpler to implement whatever behaviour I want for the tank. My problem is 1; the turret rotates the long way to the target. With this I mean that the target can be -5 degrees away in rotation and still it rotates 355 degrees instead of -5 degrees. I can't figure out why. The other problem is with the movement. It just doesn't feel right to have the tank turn while moving. I'd like to have a solution that would work as well for the AI as for the player. A blackbox function for the movement where the player only specifies in what direction it should move and it moves there under the constraints that are imposed on it. I am using the standard joystick class found in the Unity iPhone package. This is the code I'm using for the movement: public class TankFollow : MonoBehaviour { //Check angle difference and turn accordingly public GameObject followPoint; public float speed; public float turningSpeed; void Update() { transform.position = Vector3.Slerp(transform.position, followPoint.transform.position, speed * Time.deltaTime); //Calculate angle var forwardA = transform.forward; var forwardB = (followPoint.transform.position - transform.position); var angleA = Mathf.Atan2(forwardA.x, forwardA.z) * Mathf.Rad2Deg; var angleB = Mathf.Atan2(forwardB.x, forwardB.z) * Mathf.Rad2Deg; var angleDiff = Mathf.DeltaAngle(angleA, angleB); //print(angleDiff.ToString()); if (angleDiff > 5) { //Rotate to transform.Rotate(new Vector3(0, (-turningSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else if (angleDiff < 5) { transform.Rotate(new Vector3(0, (turningSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else { } transform.position = new Vector3(transform.position.x, 0, transform.position.z); } } And this is the code I'm using to rotate the turret: void LookAt() { var forwardA = -transform.right; var forwardB = (toLookAt.transform.position - transform.position); var angleA = Mathf.Atan2(forwardA.x, forwardA.z) * Mathf.Rad2Deg; var angleB = Mathf.Atan2(forwardB.x, forwardB.z) * Mathf.Rad2Deg; var angleDiff = Mathf.DeltaAngle(angleA, angleB); //print(angleDiff.ToString()); if (angleDiff - 180 > 1) { //Rotate to transform.Rotate(new Vector3(0, (turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else if (angleDiff - 180 < -1) { transform.Rotate(new Vector3(0, (-turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); print((angleDiff - 180).ToString()); } else { } } Since I want the turret reference point to turn in relation to the tank (when you rotate the body, the turret should follow and not stay locked on since it makes it impossible to control when you've got two thumbs to work with), I've made the TurretFollowPoint a child of the Turret object, which in turn is a child of the body. I'm thinking that I'm making it too difficult for myself with the reference points but I'm imagining that it's a good idea. Please be honest about this point. So I'll be grateful for any help I can get! I'm using Unity3d iPhone. Thanks!

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  • 2d tank movement and turret solution

    - by Phil
    Hi! I'm making a simple top-down tank game on the ipad where the user controls the movement of the tank with the left "joystick" and the rotation of the turret with the right one. I've spent several hours just trying to get it to work decently but now I turn to the pros :) I have two referencial objects, one for the movement and one for the rotation. The referencial objects always stay max two units away from the tank and I use them to tell the tank in what direction to move. I chose this approach to decouple movement and rotational behaviour from the raw input of the joysticks, I believe this will make it simpler to implement whatever behaviour I want for the tank. My problem is 1; the turret rotates the long way to the target. With this I mean that the target can be -5 degrees away in rotation and still it rotates 355 degrees instead of -5 degrees. I can't figure out why. The other problem is with the movement. It just doesn't feel right to have the tank turn while moving. I'd like to have a solution that would work as well for the AI as for the player. A blackbox function for the movement where the player only specifies in what direction it should move and it moves there under the constraints that are imposed on it. I am using the standard joystick class found in the Unity iPhone package. This is the code I'm using for the movement: public class TankFollow : MonoBehaviour { //Check angle difference and turn accordingly public GameObject followPoint; public float speed; public float turningSpeed; void Update() { transform.position = Vector3.Slerp(transform.position, followPoint.transform.position, speed * Time.deltaTime); //Calculate angle var forwardA = transform.forward; var forwardB = (followPoint.transform.position - transform.position); var angleA = Mathf.Atan2(forwardA.x, forwardA.z) * Mathf.Rad2Deg; var angleB = Mathf.Atan2(forwardB.x, forwardB.z) * Mathf.Rad2Deg; var angleDiff = Mathf.DeltaAngle(angleA, angleB); //print(angleDiff.ToString()); if (angleDiff > 5) { //Rotate to transform.Rotate(new Vector3(0, (-turningSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else if (angleDiff < 5) { transform.Rotate(new Vector3(0, (turningSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else { } transform.position = new Vector3(transform.position.x, 0, transform.position.z); } } And this is the code I'm using to rotate the turret: void LookAt() { var forwardA = -transform.right; var forwardB = (toLookAt.transform.position - transform.position); var angleA = Mathf.Atan2(forwardA.x, forwardA.z) * Mathf.Rad2Deg; var angleB = Mathf.Atan2(forwardB.x, forwardB.z) * Mathf.Rad2Deg; var angleDiff = Mathf.DeltaAngle(angleA, angleB); //print(angleDiff.ToString()); if (angleDiff - 180 > 1) { //Rotate to transform.Rotate(new Vector3(0, (turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); } else if (angleDiff - 180 < -1) { transform.Rotate(new Vector3(0, (-turretSpeed * Time.deltaTime),0)); //transform.rotation = new Quaternion(transform.rotation.x, transform.rotation.y + adjustment, transform.rotation.z, transform.rotation.w); print((angleDiff - 180).ToString()); } else { } } Since I want the turret reference point to turn in relation to the tank (when you rotate the body, the turret should follow and not stay locked on since it makes it impossible to control when you've got two thumbs to work with), I've made the TurretFollowPoint a child of the Turret object, which in turn is a child of the body. I'm thinking that I'm making it too difficult for myself with the reference points but I'm imagining that it's a good idea. Please be honest about this point. So I'll be grateful for any help I can get! I'm using Unity3d iPhone. Thanks!

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  • Rotation of bitmap using a frame by frame animation

    - by pengume
    Hey every one I know this has probably been asked a ton of times but I just wanted to clarify if I am approaching this correctly, since I ran into some problems rotating a bitmap. So basically I have one large bitmap that has four frames drawn on it and I only draw one at a time by looping through the bitmap by increments to animate walking. I can get the bitmap to rotate correctly when it is not moving but once the animation starts it starts to cut off alot of the image and sometimes becomes very fuzzy. I have tried public void draw(Canvas canvas,int pointerX, int pointerY) { Matrix m; if (setRotation){ // canvas.save(); m = new Matrix(); m.reset(); // spriteWidth and spriteHeight are for just the current frame showed m.setTranslate(spriteWidth / 2, spriteHeight / 2); //get and set rotation for ninja based off of joystick m.preRotate((float) GameControls.getRotation()); //create the rotated bitmap flipedSprite = Bitmap.createBitmap(bitmap , 0, 0,bitmap.getWidth(),bitmap.getHeight() , m, true); //set new bitmap to rotated ninja setBitmap(flipedSprite); // canvas.restore(); Log.d("Ninja View", "angle of rotation= " +(float) GameControls.getRotation()); setRotation = false; } And then the Draw Method here // create the destination rectangle for the ninjas current animation frame // pointerX and pointerY are from the joystick moving the ninja around destRect = new Rect(pointerX, pointerY, pointerX + spriteWidth, pointerY + spriteHeight); canvas.drawBitmap(bitmap, getSourceRect(), destRect, null); The animation is four frames long and gets incremented by 66 (the size of one of the frames on the bitmap) for every frame and then back to 0 at the end of the loop.

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  • 3D rotation matrices deform object while rotating

    - by Kevin
    I'm writing a small 3D renderer (using an orthographic projection right now). I've run into some trouble with my 3D rotation matrices. They seem to squeeze my 3D object (a box primitive) at certain angles. Here's a live demo (only tested in Google Chrome): http://dl.dropbox.com/u/109400107/3D/index.html The box is viewed from the top along the Y axis and is rotating around the X and Z axis. These are my 3 rotation matrices (Only rX and rZ are being used): var rX = new Matrix([ [1, 0, 0], [0, Math.cos(radiants), -Math.sin(radiants)], [0, Math.sin(radiants), Math.cos(radiants)] ]); var rY = new Matrix([ [Math.cos(radiants), 0, Math.sin(radiants)], [0, 1, 0], [-Math.sin(radiants), 0, Math.cos(radiants)] ]); var rZ = new Matrix([ [Math.cos(radiants), -Math.sin(radiants), 0], [Math.sin(radiants), Math.cos(radiants), 0], [0, 0, 1] ]); Before projecting the verticies I multiply them by rZ and rX like so: vert1.multiply(rZ); vert1.multiply(rX); vert2.multiply(rZ); vert2.multiply(rX); vert3.multiply(rZ); vert3.multiply(rX); The projection itself looks like this: bX = (pos.x + (vert1.x*scale)); bY = (pos.y + (vert1.z*scale)); Where "pos.x" and "pos.y" is an offset for centering the box on the screen. I just can't seem to find a solution to this and I'm still relativly new to working with Matricies. You can view the source-code of the demo page if you want to see the whole thing.

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  • Calculating a child Position, Rotation and Scale values?

    - by Sergio Plascencia
    I am making my own game editor(just for fun) anyway I have problem that I had several days trying to resolve but I have been unsuccessful. Here goes... I have an object "A": Position: (3,3,3), Rotation: (45,10,0), Scale(1,2,2.5) And an object "B": Position: (1,1,1), Rotation: (10,34,18), Scale(1.5,2,1) I now make a parent/child relationship. "B" is a child of "A": A |--B When I do the relationship I need to re-calculate the Child("B") Position, Rotation and Scale such that it maintains its current position, rotation and scale(Location in world). So for child position "B" it would now be (-2, -2, -2) since now "A" it is center and (-2, -2, -2) will keep the object in its same position. I think I got the Position and scale figure out, but rotation I cant. So I was trying to figure out what to do and what I did is opened Unity and run the same example and I did noticed that when making an abject a child object the child object did not moved at all but had its Position, Rotation and Scale values changed(Related to the parent). For example: Unity (Parent Object "A"): Position: (0,0,0) Rotation: (45,10,0) Scale: (1,1,1) Unity (Child Object "B"): Position: (0,0,0) Rotation: (0,0,0) Scale: (1,1,1) When making it a parent child relation("B" is a child of "A") the child object("B") in its Rotation values now has: X: -44.13605 Y: -14.00195 Z: 9.851074 If I plug the same values to my editor(To the child "B" rotation X, Y, Z values) the object does not move at all. So I basically need to know how did Unity arrive at those rotation values for the child(What are the calculations?). If you can help and put all the equations for the Position, Rotation or Scale then I can double check I am doing it correctly but with the Rotation I really need help. Thanks!

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  • Sprite rotation

    - by Kipras
    I'm using OpenGL and people suggest using glRotate for sprite rotation, but I find that strange. My problem with it is that it rotates the whole matrix, which sort of screws up all my collision detection and so on and so forth. Imagine I had a sprite at position (100, 100) and in position (100, 200) is an obstacle and the sprite's facing it. I rotate the sprite away from the obstacle and when move upwards my y axis, even though the projection shows like it's going away from the obstacle, the sprite will intersect it. So I don't see another way of a rotating a sprite and not screwing up all collision detection other than doing mathematical operations on the image itself. Am I right or am I missing something?

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