I am trying to implement a frustrum culling system. I have read several tutorials and think that I understand pretty well. However, somehow my code doesn't work. I suspect that there is one small mistake somewhere in my code that keeps it from working properly. Code is in C#:

class Frustrum{
	static Vector4D[] Planes;
	
	static public void Update(){ //is called every frame after the view is set with gluLookAt()

		Matrix4 modl = Matrix4.ModelviewMatrix();
		Matrix4 proj = Matrix4.ProjectionMatrix();
		Matrix4 clip = modl*proj;

		Planes = new Vector4D[6];
		Planes[0] = new Vector4D(clip[3]-clip[0],clip[7]-clip[4],clip[11]-clip[8],clip[15]-clip[12]);
		Planes[1] = new Vector4D(clip[3]+clip[0],clip[7]+clip[4],clip[11]+clip[8],clip[15]+clip[12]);
		Planes[2] = new Vector4D(clip[3]+clip[1],clip[7]+clip[5],clip[11]+clip[9],clip[15]+clip[13]);
		Planes[3] = new Vector4D(clip[3]-clip[1],clip[7]-clip[6],clip[11]-clip[9],clip[15]-clip[13]);
		Planes[4] = new Vector4D(clip[3]-clip[2],clip[7]-clip[6],clip[11]-clip[10],clip[15]-clip[14]);
		Planes[5] = new Vector4D(clip[3]+clip[2],clip[7]+clip[6],clip[11]+clip[10],clip[15]+clip[14]);
		
		foreach(Vector4D i in Planes){
			float magnitude = (float)Math.Sqrt(i.x*i.x+i.y*i.y+i.z*i.z);
			i.x /= magnitude;
			i.y /= magnitude;
			i.z /= magnitude;
			i.w /= magnitude;
		}
		
	}
		
	static public bool PointInFrustrum(Vector3D v1){
		for(int i = 0;i<6;i++){
			if((v1.x*Planes[i].x+v1.y*Planes[i].y+v1.z*Planes[i].z + Planes[i].w)<=0){
				return false;
			}
		}
		
		return true;
	}
	                         
	static public bool SphereInFrustrum(Vector3D v1, float radius){
		for(int i = 0;i<6;i++){
			float d = v1.x*Planes[i].x+v1.y*Planes[i].y+v1.z*Planes[i].z + Planes[i].w;
			if(d<=0){
				return false;
			}
		}
		
		return true;
	}
}
class Matrix4{	
	float[] Data = new float[16];

	public Matrix4(float[] d){
		Array.Copy(d,Data,16);
	}

	public static Matrix4 Multiply(Matrix4 m1, Matrix4 m2){
		Matrix4 mx = new Matrix4();
		mx.SetZero();
		for(int i = 0;i<4;i++){
			for(int j = 0; j < 4;j++){
				for(int k = 0;k<4;k++){
					mx[i,j] += m1[i,k] * m2[k,j];
				}
			}
		return mx;
	}
	public static Matrix4 ModelviewMatrix(){
		float[] d = new float[16];
		GL.glGetFloatv(GL.GL_MODELVIEW_MATRIX,d);
		return new Matrix4(d);		
	}
		
	public static Matrix4 ProjectionMatrix(){
		float[] d = new float[16];
		GL.glGetFloatv(GL.GL_PROJECTION_MATRIX,d);
		return new Matrix4(d);
		public static Matrix4 ModelviewMatrix(){
			float[] d = new float[16];
			GL.glGetFloatv(GL.GL_MODELVIEW_MATRIX,d);
			return new Matrix4(d);
			
		}
		
		public static Matrix4 ProjectionMatrix(){
			float[] d = new float[16];
			GL.glGetFloatv(GL.GL_PROJECTION_MATRIX,d);
			return new Matrix4(d);
	}

	public static Matrix4 operator*(Matrix4 m1,Matrix4 m2){
		return Multiply(m1,m2);
	}
	
	public float this[int i]{
		get{
			return Data[i];
		}
		set{
			Data[i] = value;
		}
	}
		
	public float this[int row,int column]{
		get{
			return Data[column*4+row];
		}
			
		set{
			Data[column*4+row] = value;
		}
	}
}

To test I am drawing a couple of sphers and try to clip. However, often Spheres that should be drawn are clipped as well... Any help would be greatly appreciated. [edited by - Annon on November 2, 2003 11:16:26 PM]

*bump* Does nobody have an idea?

in SphereInFrustrum: "if(d<=0)" should be something like "if(d<=-radius)"


You should never let your fears become the boundaries of your dreams.

Thanks DarkWind for pointing out this mistake. I corrected it and it still doesnt work...