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POXNA 4.0 3D Collision
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copied!<p><br> I've been trying to work on a 3d forward-runner game (like temple run) in XNA 4.0. <br> I'm hitting a bit of a brick wall, so any help would be much appreciated! <br> Currently, I'm using my own method for collision detection, which requires the dimensions for each model to be hard-coded into the collision method. I've tried using the code from Microsoft, directly below, but it always returns false:</p> <pre><code> static bool CheckForCollisions(Entity c1, Entity c2) { for (int i = 0; i < c1.body.Meshes.Count; i++) { // Check whether the bounding boxes of the two cubes intersect. BoundingSphere c1BoundingSphere = c1.body.Meshes[i].BoundingSphere; c1BoundingSphere.Center += c1.position; for (int j = 0; j < c2.body.Meshes.Count; j++) { BoundingSphere c2BoundingSphere = c2.body.Meshes[j].BoundingSphere; c2BoundingSphere.Center += c2.position; if (c1BoundingSphere.Intersects(c2BoundingSphere)) { return true; } } } return false; } </code></pre> <p>This was taken and modified very slightly from, <a href="http://msdn.microsoft.com/en-us/library/bb203906.aspx" rel="nofollow">Here</a> My Entity class goes as follows.</p> <p>Code of mine which I think is relevant would be:</p> <pre><code> public class Entity { public int rowID; public Model body; public Vector3 position; public float rotation = 0f; public float rotatePerFrame = 0f; protected internal float toRight = 0; protected internal float toLeft = 0; protected internal float forward = 0; protected internal float back = 0; protected internal float bottom = 0; protected internal float top = 0; public void setDimensions(float right, float left, float front, float back, float top, float bottom) { this.toRight = right; this.toLeft = left; this.forward = front; this.back = back; this.top = top; this.bottom = bottom; } public Entity RotateEnt(Entity e,float degrees)//Psuedo-only accurate to 90 degrees. { float actual = MathHelper.ToDegrees(degrees); switch ((int)actual) { case 0: break; case 90: // float temp = e.forward; // e.forward = e.toLeft; // e.toLeft =e.back ; // e.back = e.toRight; // e.toRight = temp; float temp = e.forward; e.forward = e.toRight; e.toRight = e.back; e.back = e.toLeft; e.toLeft = temp; break; case 180: e.forward = e.back; e.back = e.forward; e.toRight = e.toLeft; e.toLeft = e.toRight; break; default: //case: 270 e.toRight = e.forward; e.back = e.toRight; e.toLeft = e.back; e.forward = e.toLeft; break; } return e; } public bool Collides(Entity e) { Entity c1 = RotateEnt(this, this.rotation); Entity c2 = RotateEnt(e, e.rotation); float myRightest = c1.position.X + c1.toRight; float myLeftest = c1.position.X - c1.toLeft; float hisRightest = c2.position.X + c2.toRight; float hisLeftest = c2.position.X - c2.toLeft; if(Collides1D(myLeftest, myRightest, hisLeftest, hisRightest)) { float myTop = c1.position.Y + c1.top; float myBottom = c1.position.Y - c1.bottom; float hisTop = c2.position.Y + c2.top; float hisBottom = c2.position.Y - c2.bottom; if (Collides1D(myBottom, myTop, hisBottom, hisTop)) { float myBack = c1.position.Z - c1.forward; float myForward = c1.position.Z + c1.back; float hisBack = c2.position.Z - c2.forward; float hisForward = c2.position.Z + c2.back; if (Collides1D(myBack, myForward, hisBack, hisForward)) { return true; } } } return false; } } static bool Collides1D(float left1, float right1, float left2, float right2) { if (left1 >= left2 && left1 <= right2) return true; if (right1 >= left2 && right1 <= right2) return true; if (left2 >= left1 && left2 <= right1) return true; if (right2 >= left1 && right2 <= right1) return true; return false; } </code></pre> <p>My own method has been screwing up also, when trying to rotate models.<br> Ideally, it would be good to know what is wrong with the code from Microsoft, so that I can use it wherever, without worrying about hard-coding in object dimensions.<br> If anyone can see a fast fix to my own basic collision detection method, that would also be great.<br> I've looked at the Reimers tutorials, but I'm not getting them at the moment, maybe I've been staring at my own code for too long...<br> Any other information you want, I can try and supply. I can upload the models also, if that's the problem. I'm using models from Maya, exported as FBX. I'm using MSVS 2010. Thanks very much!<br> Jack</p>

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