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`===============
`EXTRACT FRUSTUM
`===============
function extractfrustum()

   t# = 0
   ClipRange = 1
   ProjectionMatrix = 1
   ViewMatrix = 2
   ClipMatrix = 3
   null=MAKE MATRIX4(ProjectionMatrix)
   null=MAKE MATRIX4(ViewMatrix)
   null=MAKE MATRIX4(ClipMatrix)
   `get the screen space matrix
   Projection Matrix4 ProjectionMatrix
   `get the camera space matrix
   VIEW MATRIX4 ViewMatrix
   `multiply the camera space matrix by the screen space matrix
   `to get the clip matrix to get the frustum planes from
   MULTIPLY MATRIX4 ClipMatrix, ViewMatrix, ProjectionMatrix
   `assign the clip matrix elements to an array so we can use them
   for i = 0 to 15
      clip(i) = DK Get Matrix4 Element( ClipMatrix, i )
   next i

   `/* Extract the numbers for the RIGHT plane */
   frustum(0,0) = clip( 3) - clip( 0)
   frustum(0,1) = clip( 7) - clip( 4)
   frustum(0,2) = clip(11) - clip( 8)
   frustum(0,3) = clip(15) - clip(12)

   `/* Normalize the result */
   rangeClipx# = frustum(0,0)
   rangeClipy# = frustum(0,1)
   rangeClipz# = frustum(0,2)

   `*** Note to self, could optimize this? all done with vectors?
   null=make vector3(ClipRange)
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum(0,0) = frustum(0,0) / t#
   frustum(0,1) = frustum(0,1) / t#
   frustum(0,2) = frustum(0,2) / t#
   frustum(0,3) = frustum(0,3) / t#

   `/* Extract the numbers for the LEFT plane */
   frustum(1,0) = clip( 3) + clip( 0)
   frustum(1,1) = clip( 7) + clip( 4)
   frustum(1,2) = clip(11) + clip( 8)
   frustum(1,3) = clip(15) + clip(12)

   `/* Normalize the result */
   rangeClipx# = frustum(1,0)
   rangeClipy# = frustum(1,1)
   rangeClipz# = frustum(1,2)
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum(1,0) = frustum(1,0) / t#
   frustum(1,1) = frustum(1,1) / t#
   frustum(1,2) = frustum(1,2) / t#
   frustum(1,3) = frustum(1,3) / t#

   `/* Extract the BOTTOM plane */
   frustum(2,0) = clip( 3) + clip( 1)
   frustum(2,1) = clip( 7) + clip( 5)
   frustum(2,2) = clip(11) + clip( 9)
   frustum(2,3) = clip(15) + clip(13)

   `/* Normalize the result */
   rangeClipx# = frustum(2,0)
   rangeClipy# = frustum(2,1)
   rangeClipz# = frustum(2,2)
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum(2,0) = frustum(2,0) / t#
   frustum(2,1) = frustum(2,1) / t#
   frustum(2,2) = frustum(2,2) / t#
   frustum(2,3) = frustum(2,3) / t#

   `/* Extract the TOP plane */
   frustum(3,0) = clip( 3) - clip( 1)
   frustum(3,1) = clip( 7) - clip( 5)
   frustum(3,2) = clip(11) - clip( 9)
   frustum(3,3) = clip(15) - clip(13)

   `/* Normalize the result */
   rangeClipx# = frustum(3,0)
   rangeClipy# = frustum(3,1)
   rangeClipz# = frustum(3,2)
   `get distance from corner to corner of plane
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   `use distance to normalize data
   frustum(3,0) = frustum(3,0) / t#
   frustum(3,1) = frustum(3,1) / t#
   frustum(3,2) = frustum(3,2) / t#
   frustum(3,3) = frustum(3,3) / t#

   `/* Extract the FAR plane */
   frustum(4,0) = clip( 3) - clip( 2)
   frustum(4,1) = clip( 7) - clip( 6)
   frustum(4,2) = clip(11) - clip(10)
   frustum(4,3) = clip(15) - clip(14)

   `/* Normalize the result */
   rangeClipx# = frustum(4,0)
   rangeClipy# = frustum(4,1)
   rangeClipz# = frustum(4,2)
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum(4,0) = frustum(4,0) / t#
   frustum(4,1) = frustum(4,1) / t#
   frustum(4,2) = frustum(4,2) / t#
   frustum(4,3) = frustum(4,3) / t#

   `/* Extract the NEAR plane */
   frustum(5,0) = clip( 3) + clip( 2)
   frustum(5,1) = clip( 7) + clip( 6)
   frustum(5,2) = clip(11) + clip(10)
   frustum(5,3) = clip(15) + clip(14)

   `/* Normalize the result */
   rangeClipx# = frustum(5,0)
   rangeClipy# = frustum(5,1)
   rangeClipz# = frustum(5,2)
   set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
   rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum(5,0) = frustum(5,0) / t#
   frustum(5,1) = frustum(5,1) / t#
   frustum(5,2) = frustum(5,2) / t#
   frustum(5,3) = frustum(5,3) / t#
   null=delete vector3(ClipRange)

endfunction

`=================
`SPHERE IN FRUSTUM
`=================
`returns 0 for outside and distance of sphere from camera if in
function sphereinfrustum( x#, y#, z#, radius# )

   p = 0
   d# = 0.0
   result# = 0
   for p = 0 to 5
      d# = (frustum(p,0) * x#) + (frustum(p,1) * y#) + (frustum(p,2) * z#) + frustum(p,3)
      if d# <= 0-radius#
         exitfunction result#
      endif
   next p
   result# = d# + radius#;

endfunction result#

float frustum[6][4];
float clip[16];

//==============
//DK GET ELEMENT
//==============
float DK_Vectors_GetMatrixElement( int Matrix, int Element ) {
	float res = 0.0;
	D3DXMATRIX mat = dbGetMatrix(Matrix);
	if (Element>=0 && Element<=15) res = mat[Element];
	return res;
} //end DK()

//=================
//EXTRACT FRUSTUM()
//=================
void extractFrustum( void ) {

	float t = 0.0f; int clipRange = 1; 

	//matrix id's
    int projectionMatrix = 1;
    int viewMatrix = 2;
    int clipMatrix = 3;

	int null;
	null = dbMakeMatrix4(projectionMatrix);
	null = dbMakeMatrix4(viewMatrix);
	null = dbMakeMatrix4(clipMatrix);
   
	//get the screen space matrix
	dbProjectionMatrix4( projectionMatrix );
    //get the camera space matrix
	dbViewMatrix4( viewMatrix );
    //multiply the camera space matrix by the screen space matrix
    //to get the clip matrix to get the frustum planes from
	dbMultiplyMatrix4(clipMatrix, viewMatrix, projectionMatrix);

    //assign the clip matrix elements to an array so we can use them
	for (int i = 0; i < 16; i++) {
		clip[i] = DK_Vectors_GetMatrixElement( clipMatrix, i );
	}
	
	//extract the numbers for the RIGHT plane
	frustum[0][0] = clip[3] - clip[0];
	frustum[0][1] = clip[7] - clip[4];
	frustum[0][2] = clip[11] - clip[8];
	frustum[0][3] = clip[15] - clip[12];

	//normalize the result
	float rangeClipX = frustum[0][0];
	float rangeClipY = frustum[0][1];
	float rangeClipZ = frustum[0][2];
	//*** note to self, could optimize this? all done with vectors?
	null = dbMakeVector3(clipRange);
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ);
	float rangeClipResult	=	dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[0][0] = frustum[0][0] / t;
	frustum[0][1] = frustum[0][1] / t;
	frustum[0][2] = frustum[0][2] / t;
	frustum[0][3] = frustum[0][3] / t;

	//extract the numbers for the LEFT plane
	frustum[1][0] = clip[3] + clip[0];
	frustum[1][1] = clip[7] + clip[4];
	frustum[1][2] = clip[11] + clip[8];
	frustum[1][3] = clip[15] + clip[12];

	//normalize the result
	rangeClipX = frustum[1][0];
	rangeClipY = frustum[1][1];
	rangeClipZ = frustum[1][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[1][0] = frustum[1][0] / t;
	frustum[1][1] = frustum[1][1] / t;
	frustum[1][2] = frustum[1][2] / t;
	frustum[1][3] = frustum[1][3] / t;

	//extract the BOTTOM plane
	frustum[2][0] = clip[3] + clip[1];
	frustum[2][1] = clip[7] + clip[5];
	frustum[2][2] = clip[11] + clip[9];
	frustum[2][3] = clip[15] + clip[13];

	//normalize the result
	rangeClipX = frustum[2][0];
	rangeClipY = frustum[2][1];
	rangeClipZ = frustum[2][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[2][0] = frustum[2][0] / t;
	frustum[2][1] = frustum[2][1] / t;
	frustum[2][2] = frustum[2][2] / t;
	frustum[2][3] = frustum[2][3] / t;

	//extract the TOP plane
	frustum[3][0] = clip[3] - clip[1];
	frustum[3][1] = clip[7] - clip[5];
	frustum[3][2] = clip[11] - clip[9];
	frustum[3][3] = clip[15] - clip[13];

	//normalize the result
	rangeClipX = frustum[3][0];
	rangeClipY = frustum[3][1];
	rangeClipZ = frustum[3][2];
	//get distance from corner to corner of plane
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	//use distance to normalize data
	frustum[3][0] = frustum[3][0] / t;
	frustum[3][1] = frustum[3][1] / t;
	frustum[3][2] = frustum[3][2] / t;
	frustum[3][3] = frustum[3][3] / t;

	//extract the FAR plane
	frustum[4][0] = clip[3] - clip[2];
	frustum[4][1] = clip[7] - clip[6];
	frustum[4][2] = clip[11] - clip[10];
	frustum[4][3] = clip[15] - clip[14];

	//normalize the result
	rangeClipX = frustum[4][0];
	rangeClipY = frustum[4][1];
	rangeClipZ = frustum[4][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[4][0] = frustum[4][0] / t;
	frustum[4][1] = frustum[4][1] / t;
	frustum[4][2] = frustum[4][2] / t;
	frustum[4][3] = frustum[4][3] / t;

	//extract the NEAR plane
	frustum[5][0] = clip[3] + clip[2];
	frustum[5][1] = clip[7] + clip[6];
	frustum[5][2] = clip[11] + clip[10];
	frustum[5][3] = clip[15] + clip[14];

	//normalize the result
	rangeClipX = frustum[5][0];
	rangeClipY = frustum[5][1];
	rangeClipZ = frustum[5][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[5][0] = frustum[5][0] / t;
	frustum[5][1] = frustum[5][1] / t;
	frustum[5][2] = frustum[5][2] / t;
	frustum[5][3] = frustum[5][3] / t;

	null = dbDeleteVector3(clipRange);

} //end extractFrustum()

//=================
//IS BOX IN FRUSTUM
//=================
int isBoxInFrustum ( float x, float y, float z, float xSize, float ySize, float zSize ) {

	int a = 0;

	//for all plains
	for (int p = 0; p < 6; p++) {
		if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
			a = 1;
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}

		//
		if (a == 0) p = 6;

	} //next p

	if (a ==0) {return 0;} else {return 1;}

} //end isBoxInFrustum();

#include "DarkSDK.h"

float frustum[6][4];
void extractFrustum( void );
int isBoxInFrustum(float, float, float, float, float, float);


void DarkSDK ( void )
{
	dbSyncRate(60);
	dbMakeObjectCube(1,10);

	while ( !dbEscapeKey ( ) )
	{

		int FPS = dbScreenFPS(); if (FPS == 0) FPS = 1;
		if (dbMouseClick() == 1) dbMoveCamera( 10/float(FPS) );
		if (dbMouseClick() == 2) dbMoveCamera( -10/float(FPS) );
		dbRotateCamera( dbWrapValue(dbCameraAngleX()-dbMouseMoveY()), dbWrapValue(dbCameraAngleY()+dbMouseMoveX()),0);

		extractFrustum();

		int a = isBoxInFrustum(0.0f,0.0f,0.0f,5.0f,5.0f,5.0f);
		dbText(0,0,dbStr(a));
		dbSync ( );
	}
}

//==============
//DK GET ELEMENT
//==============
float DK_Vectors_GetMatrixElement( int Matrix, int Element ) {
	float res = 0.0;
	D3DXMATRIX mat = dbGetMatrix(Matrix);
	if (Element>=0 && Element<=15) res = mat[Element];
	return res;
} //end DK()

//=================
//EXTRACT FRUSTUM()
//=================
void extractFrustum( void ) {

	float t = 0.0f; int clipRange = 1; 
	float clip[16];

	//matrix id's
	int projectionMatrix = 1;
	int viewMatrix = 2;
	int clipMatrix = 3;

	int null;
	null = dbMakeMatrix4(projectionMatrix);
	null = dbMakeMatrix4(viewMatrix);
	null = dbMakeMatrix4(clipMatrix);
   
	//get the screen space matrix
	dbProjectionMatrix4( projectionMatrix );
	//get the camera space matrix
	dbViewMatrix4( viewMatrix );
	//multiply the camera space matrix by the screen space matrix
	//to get the clip matrix to get the frustum planes from
	dbMultiplyMatrix4(clipMatrix, viewMatrix, projectionMatrix);
	//dbMultiplyMatrix4(clipMatrix, projectionMatrix, viewMatrix);

    	//assign the clip matrix elements to an array so we can use them
	for (int i = 0; i < 16; i++) {
		clip[i] = DK_Vectors_GetMatrixElement( clipMatrix, i );
	}
	
	//extract the numbers for the RIGHT plane
	frustum[0][0] = clip[3] - clip[0];
	frustum[0][1] = clip[7] - clip[4];
	frustum[0][2] = clip[11] - clip[8];
	frustum[0][3] = clip[15] - clip[12];

	//normalize the result
	float rangeClipX = frustum[0][0];
	float rangeClipY = frustum[0][1];
	float rangeClipZ = frustum[0][2];
	//*** note to self, could optimize this? all done with vectors?
	null = dbMakeVector3(clipRange);
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ);
	float rangeClipResult	=	dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[0][0] = frustum[0][0] / t;
	frustum[0][1] = frustum[0][1] / t;
	frustum[0][2] = frustum[0][2] / t;
	frustum[0][3] = frustum[0][3] / t;

	//extract the numbers for the LEFT plane
	frustum[1][0] = clip[3] + clip[0];
	frustum[1][1] = clip[7] + clip[4];
	frustum[1][2] = clip[11] + clip[8];
	frustum[1][3] = clip[15] + clip[12];

	//normalize the result
	rangeClipX = frustum[1][0];
	rangeClipY = frustum[1][1];
	rangeClipZ = frustum[1][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[1][0] = frustum[1][0] / t;
	frustum[1][1] = frustum[1][1] / t;
	frustum[1][2] = frustum[1][2] / t;
	frustum[1][3] = frustum[1][3] / t;

	//extract the BOTTOM plane
	frustum[2][0] = clip[3] + clip[1];
	frustum[2][1] = clip[7] + clip[5];
	frustum[2][2] = clip[11] + clip[9];
	frustum[2][3] = clip[15] + clip[13];

	//normalize the result
	rangeClipX = frustum[2][0];
	rangeClipY = frustum[2][1];
	rangeClipZ = frustum[2][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[2][0] = frustum[2][0] / t;
	frustum[2][1] = frustum[2][1] / t;
	frustum[2][2] = frustum[2][2] / t;
	frustum[2][3] = frustum[2][3] / t;

	//extract the TOP plane
	frustum[3][0] = clip[3] - clip[1];
	frustum[3][1] = clip[7] - clip[5];
	frustum[3][2] = clip[11] - clip[9];
	frustum[3][3] = clip[15] - clip[13];

	//normalize the result
	rangeClipX = frustum[3][0];
	rangeClipY = frustum[3][1];
	rangeClipZ = frustum[3][2];
	//get distance from corner to corner of plane
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	//use distance to normalize data
	frustum[3][0] = frustum[3][0] / t;
	frustum[3][1] = frustum[3][1] / t;
	frustum[3][2] = frustum[3][2] / t;
	frustum[3][3] = frustum[3][3] / t;

	//extract the FAR plane
	frustum[4][0] = clip[3] - clip[2];
	frustum[4][1] = clip[7] - clip[6];
	frustum[4][2] = clip[11] - clip[10];
	frustum[4][3] = clip[15] - clip[14];

	//normalize the result
	rangeClipX = frustum[4][0];
	rangeClipY = frustum[4][1];
	rangeClipZ = frustum[4][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[4][0] = frustum[4][0] / t;
	frustum[4][1] = frustum[4][1] / t;
	frustum[4][2] = frustum[4][2] / t;
	frustum[4][3] = frustum[4][3] / t;

	//extract the NEAR plane
	frustum[5][0] = clip[3] + clip[2];
	frustum[5][1] = clip[7] + clip[6];
	frustum[5][2] = clip[11] + clip[10];
	frustum[5][3] = clip[15] + clip[14];

	//normalize the result
	rangeClipX = frustum[5][0];
	rangeClipY = frustum[5][1];
	rangeClipZ = frustum[5][2];
	dbSetVector3( clipRange, rangeClipX, rangeClipY, rangeClipZ );
	rangeClipResult = dbLengthVector3(clipRange);
	t = rangeClipResult;
	frustum[5][0] = frustum[5][0] / t;
	frustum[5][1] = frustum[5][1] / t;
	frustum[5][2] = frustum[5][2] / t;
	frustum[5][3] = frustum[5][3] / t;

	null = dbDeleteVector3(clipRange);

} //end extractFrustum()

//=================
//IS BOX IN FRUSTUM
//=================
int isBoxInFrustum ( float x, float y, float z, float xSize, float ySize, float zSize ) {

	int a = 0;

	//for all plains
	for (int p = 0; p < 6; p++) {
		if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
			a = 1;
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z - zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y - ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x - xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}
		if (a == 0) {
			if ( (frustum[p][0] * (x + xSize)) + (frustum[p][1] * (y + ySize)) + (frustum[p][2] * (z + zSize)) + frustum[p][3] > 0 ) {
				a = 1;
			}
		}

		//
		if (a == 0) p = 6;

	} //next p

	if (a ==0) {return 0;} else {return 1;}

} //end isBoxInFrustum();

set window on
set display mode 800, 600, 32
sync on : Sync rate 60
backdrop on
autocam off
set camera range 0.5, 3000
position camera 0, 0, -25

make object cube 1, 10
set object wireframe 1, 1

`dim arrays for culling
dim frustum#(5,3)
dim testdata#(31)
dim clip#(15)
`make vectors and matrix4 for distance and frustum checks
ProjectionMatrix = 1
ViewMatrix = 2
ClipMatrix = 3
ClipRange = 4
null=MAKE MATRIX4(ProjectionMatrix)
null=MAKE MATRIX4(ClipMatrix)
null=MAKE MATRIX4(ViewMatrix)
null=make vector3(ClipRange)
`get the screen space matrix (you don't need to update this matrix4 unless
`resolution or aspect etc changes
Projection Matrix4 ProjectionMatrix

` main program loop
do
   rotate camera camera angle x()+(mousemovey()/2),camera angle y()+(mousemovex()/2),0
   if camera angle x()>90 then xrotate camera 90
   if camera angle x()<-90 then xrotate camera -90
	
	mval = mouseclick()
	if mval = 1
		move camera 1
	endif
	if mval = 2
		move camera -1
	endif
	
	gosub Extractfrustum
	resultcheck = CubeInfrustum( 0, 0, 0, 5 )
	set cursor 0,0
	print resultcheck
	`press the 1 key for clip matrix values
	if keystate(2) = 1
		for i = 0 to 15 step 2
			print clip#(i)," : ",clip#(i+1)
		next i
	endif
	`press the 2 key for view matrix values
	if keystate(3) = 1
		for i = 0 to 15 step 2
			print testdata#(i)," : ",testdata#(i+1)
		next i
	endif
	`press the 3 key for Projection matrix values
	if keystate(4) = 1
		for i = 16 to 31 step 2
			print testdata#(i)," : ",testdata#(i+1)
		next i
	endif
   sync
loop
null=delete matrix4(ProjectionMatrix)
null=delete matrix4(ViewMatrix)
null=delete matrix4(ClipMatrix)
null=delete vector3(ClipRange)
end

Extractfrustum:
   t# = 0
   `get the camera space matrix
   VIEW MATRIX4 ViewMatrix
   `multiply the camera space matrix by the screen space matrix
   `to get the clip matrix to get the frustum planes from
   MULTIPLY MATRIX4 ClipMatrix, ViewMatrix, ProjectionMatrix
   `assign the clip matrix elements to an array so we can use them
   for i = 0 to 15
      clip#(i) = DK Get Matrix4 Element( ClipMatrix, i )
   next i
   for i = 0 to 15
      testdata#(i) = DK Get Matrix4 Element( ViewMatrix, i )
   next i
   for i = 0 to 15
      testdata#(i+16) = DK Get Matrix4 Element( ProjectionMatrix, i )
   next i
   `/* Extract the numbers for the RIGHT plane */
   frustum#(0,0) = clip#( 3) - clip#( 0);
   frustum#(0,1) = clip#( 7) - clip#( 4);
   frustum#(0,2) = clip#(11) - clip#( 8);
   frustum#(0,3) = clip#(15) - clip#(12);
   `/* Normalize the result */
   rangeClipx# = frustum#(0,0)
   rangeClipy# = frustum#(0,1)
   rangeClipz# = frustum#(0,2)
	set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
	rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum#(0,0) = frustum#(0,0) / t#
   frustum#(0,1) = frustum#(0,1) / t#
   frustum#(0,2) = frustum#(0,2) / t#
   frustum#(0,3) = frustum#(0,3) / t#

   `/* Extract the numbers for the LEFT plane */
   frustum#(1,0) = clip#( 3) + clip#( 0);
   frustum#(1,1) = clip#( 7) + clip#( 4);
   frustum#(1,2) = clip#(11) + clip#( 8);
   frustum#(1,3) = clip#(15) + clip#(12);

   `/* Normalize the result */
	`use distance from right plane to normalize data
   frustum#(1,0) = frustum#(1,0) / t#
   frustum#(1,1) = frustum#(1,1) / t#
   frustum#(1,2) = frustum#(1,2) / t#
   frustum#(1,3) = frustum#(1,3) / t#

   `/* Extract the BOTTOM plane */
   frustum#(2,0) = clip#( 3) + clip#( 1);
   frustum#(2,1) = clip#( 7) + clip#( 5);
   frustum#(2,2) = clip#(11) + clip#( 9);
   frustum#(2,3) = clip#(15) + clip#(13);

   `/* Normalize the result */
   rangeClipx# = frustum#(2,0)
   rangeClipy# = frustum#(2,1)
   rangeClipz# = frustum#(2,2)
	set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
	rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum#(2,0) = frustum#(2,0) / t#
   frustum#(2,1) = frustum#(2,1) / t#
   frustum#(2,2) = frustum#(2,2) / t#
   frustum#(2,3) = frustum#(2,3) / t#

   `/* Extract the TOP plane */
   frustum#(3,0) = clip#( 3) - clip#( 1);
   frustum#(3,1) = clip#( 7) - clip#( 5);
   frustum#(3,2) = clip#(11) - clip#( 9);
   frustum#(3,3) = clip#(15) - clip#(13);

   `/* Normalize the result */
   `use distance from bottom plane to normalize data
   frustum#(3,0) = frustum#(3,0) / t#
   frustum#(3,1) = frustum#(3,1) / t#
   frustum#(3,2) = frustum#(3,2) / t#
   frustum#(3,3) = frustum#(3,3) / t#

   `/* Extract the FAR plane */
   frustum#(4,0) = clip#( 3) - clip#( 2);
   frustum#(4,1) = clip#( 7) - clip#( 6);
   frustum#(4,2) = clip#(11) - clip#(10);
   frustum#(4,3) = clip#(15) - clip#(14);

   `/* Normalize the result */
   rangeClipx# = frustum#(4,0)
   rangeClipy# = frustum#(4,1)
   rangeClipz# = frustum#(4,2)
	set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
	rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum#(4,0) = frustum#(4,0) / t#
   frustum#(4,1) = frustum#(4,1) / t#
   frustum#(4,2) = frustum#(4,2) / t#
   frustum#(4,3) = frustum#(4,3) / t#

   `/* Extract the NEAR plane */
   frustum#(5,0) = clip#( 3) + clip#( 2);
   frustum#(5,1) = clip#( 7) + clip#( 6);
   frustum#(5,2) = clip#(11) + clip#(10);
   frustum#(5,3) = clip#(15) + clip#(14);

   `/* Normalize the result */
   rangeClipx# = frustum#(5,0)
   rangeClipy# = frustum#(5,1)
   rangeClipz# = frustum#(5,2)
	set vector3 ClipRange, rangeClipx#, rangeClipy#, rangeClipz#
	rangeClipresult#=length vector3(ClipRange)
   t# = rangeClipresult#
   frustum#(5,0) = frustum#(5,0) / t#
   frustum#(5,1) = frustum#(5,1) / t#
   frustum#(5,2) = frustum#(5,2) / t#
   frustum#(5,3) = frustum#(5,3) / t#
return

function CubeInfrustum( x#, y#, z#, size# )
	`test each point of the box against each plane
   for p = 0 to 5
      a = 0
      if (frustum#(p,0) * (x# - size#)) + (frustum#(p,1) * (y# - size#)) + (frustum#(p,2) * (z# - size#)) + frustum#(p,3) > 0
         a = 1
      endif
      if a = 0
         if (frustum#(p,0) * (x# + size#)) + (frustum#(p,1) * (y# - size#)) + (frustum#(p,2) * (z# - size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# - size#)) + (frustum#(p,1) * (y# + size#)) + (frustum#(p,2) * (z# - size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# + size#)) + (frustum#(p,1) * (y# + size#)) + (frustum#(p,2) * (z# - size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# - size#)) + (frustum#(p,1) * (y# - size#)) + (frustum#(p,2) * (z# + size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# + size#)) + (frustum#(p,1) * (y# - size#)) + (frustum#(p,2) * (z# + size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# - size#)) + (frustum#(p,1) * (y# + size#)) + (frustum#(p,2) * (z# + size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      if a = 0
         if (frustum#(p,0) * (x# + size#)) + (frustum#(p,1) * (y# + size#)) + (frustum#(p,2) * (z# + size#)) + frustum#(p,3) > 0
            a = 1
         endif
      endif
      `if none of the points are in then exit test
      if a = 0
      	exit
      endif
   next p
   `if exited from none in give 0 as a result
	if a = 0
		exitfunction 0
	endif
	`else give a 1
endfunction 1

Clipdata:
1.2491440773 : 0
0 : 0
0 : 1.66552555561
0 : 0
0 : 0
1.00016653538 : 0.999999940395
0 : 0
24.5040798187 : 24.9999980927

Viewdata:
0.999999940395 : 0
0 : 0
0 : 0.999999940395
0 : 0
0 : 0
0.999999940395 : 0
-0 : -0
24.9999980927 : 1

Projdata:
1.24914419651 : 0
0 : 0
0 : 1.66552567482
0 : 0
0 : 0
1.00016665459 : 1
0 : 0
-0.500083327293 : 0

   	//matrix id's
    int projectionMatrix = 1;
    int viewMatrix = 2;

	int null;
	null = dbMakeMatrix4(projectionMatrix);
	null = dbMakeMatrix4(viewMatrix);

   /* Get the current PROJECTION matrix from OpenGL */
   //glGetFloatv( GL_PROJECTION_MATRIX, proj );
	dbProjectionMatrix4( projectionMatrix );

	for (int i = 0; i < 16; i++) {
		proj[i] = DK_Vectors_GetMatrixElement( projectionMatrix, i );
	}


   /* Get the current MODELVIEW matrix from OpenGL */
   //glGetFloatv( GL_MODELVIEW_MATRIX, modl );

	dbViewMatrix4( viewMatrix );

	for (int i = 0; i < 16; i++) {
		modl[i] = DK_Vectors_GetMatrixElement( viewMatrix, i );
	}

set window on
set display mode 800, 600, 32
sync on : Sync rate 60
backdrop on
autocam off
set camera range 0.5, 3000
position camera 0, 0, -25

bool CubeInFrustum( float x, float y, float z,float xSize, float ySize, float zSize )
{
   int p;

   for( p = 0; p < 6; p++ )
   {
      if( frustum[p][0] * (x - xSize) + frustum[p][1] * (y - ySize) + frustum[p][2] * (z - zsSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x + xSize) + frustum[p][1] * (y - ySize) + frustum[p][2] * (z - zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x - xSize) + frustum[p][1] * (y + ySize) + frustum[p][2] * (z - zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x + xSize) + frustum[p][1] * (y + ySize) + frustum[p][2] * (z - zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x - xSize) + frustum[p][1] * (y - ySize) + frustum[p][2] * (z + zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x + xSize) + frustum[p][1] * (y - ySize) + frustum[p][2] * (z + zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x - xSize) + frustum[p][1] * (y + ySize) + frustum[p][2] * (z + zSize) + frustum[p][3] > 0 )
         continue;
      if( frustum[p][0] * (x + xSize) + frustum[p][1] * (y + ySize) + frustum[p][2] * (z + zSize) + frustum[p][3] > 0 )
         continue;
      return false;
   }
   return true;
}