path: root/src/Frustum.cpp

#include <cmath>
#include <GL/gl.h>

#include "Frustum.h"

void FRUSTUM::
	GetFrustum() {
	float projmatrix[16];
	float mvmatrix[16];
	float clip[16];
	float t;

	glGetFloatv(GL_PROJECTION_MATRIX, projmatrix);
	glGetFloatv(GL_MODELVIEW_MATRIX, mvmatrix);

	// Combine the matrices
	clip[0]	= mvmatrix[0] * projmatrix[0] + mvmatrix[1] * projmatrix[4] + mvmatrix[2] * projmatrix[8] + mvmatrix[3] * projmatrix[12];
	clip[1] = mvmatrix[0] * projmatrix[1] + mvmatrix[1] * projmatrix[5] + mvmatrix[2] * projmatrix[9] + mvmatrix[3] * projmatrix[13];
	clip[2] = mvmatrix[0] * projmatrix[2] + mvmatrix[1] * projmatrix[6] + mvmatrix[2] * projmatrix[10] + mvmatrix[3] * projmatrix[14];
	clip[3] = mvmatrix[0] * projmatrix[3] + mvmatrix[1] * projmatrix[7] + mvmatrix[2] * projmatrix[11] + mvmatrix[3] * projmatrix[15];

	clip[4] = mvmatrix[4] * projmatrix[0] + mvmatrix[5] * projmatrix[4] + mvmatrix[6] * projmatrix[8] + mvmatrix[7] * projmatrix[12];
	clip[5] = mvmatrix[4] * projmatrix[1] + mvmatrix[5] * projmatrix[5] + mvmatrix[6] * projmatrix[9] + mvmatrix[7] * projmatrix[13];
	clip[6] = mvmatrix[4] * projmatrix[2] + mvmatrix[5] * projmatrix[6] + mvmatrix[6] * projmatrix[10] + mvmatrix[7] * projmatrix[14];
	clip[7] = mvmatrix[4] * projmatrix[3] + mvmatrix[5] * projmatrix[7] + mvmatrix[6] * projmatrix[11] + mvmatrix[7] * projmatrix[15];

	clip[8] = mvmatrix[8] * projmatrix[0] + mvmatrix[9] * projmatrix[4] + mvmatrix[10] * projmatrix[8] + mvmatrix[11] * projmatrix[12];
	clip[9] = mvmatrix[8] * projmatrix[1] + mvmatrix[9] * projmatrix[5] + mvmatrix[10] * projmatrix[9] + mvmatrix[11] * projmatrix[13];
	clip[10] = mvmatrix[8] * projmatrix[2] + mvmatrix[9] * projmatrix[6] + mvmatrix[10] * projmatrix[10] + mvmatrix[11] * projmatrix[14];
	clip[11] = mvmatrix[8] * projmatrix[3] + mvmatrix[9] * projmatrix[7] + mvmatrix[10] * projmatrix[11] + mvmatrix[11] * projmatrix[15];

	clip[12] = mvmatrix[12] * projmatrix[0] + mvmatrix[13] * projmatrix[4] + mvmatrix[14] * projmatrix[8] + mvmatrix[15] * projmatrix[12];
	clip[13] = mvmatrix[12] * projmatrix[1] + mvmatrix[13] * projmatrix[5] + mvmatrix[14] * projmatrix[9] + mvmatrix[15] * projmatrix[13];
	clip[14] = mvmatrix[12] * projmatrix[2] + mvmatrix[13] * projmatrix[6] + mvmatrix[14] * projmatrix[10] + mvmatrix[15] * projmatrix[14];
	clip[15] = mvmatrix[12] * projmatrix[3] + mvmatrix[13] * projmatrix[7] + mvmatrix[14] * projmatrix[11] + mvmatrix[15] * projmatrix[15];

	// 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];

	// 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];

	// 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];

	// 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];

	// 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];

	// 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 right plane */
	t = sqrtf(frustum[0][0]*frustum[0][0]
		+ frustum[0][1]*frustum[0][1]
		+ frustum[0][2]*frustum[0][2]);
	frustum[0][0] /= t;
	frustum[0][1] /= t;
	frustum[0][2] /= t;
	frustum[0][3] /= t;

	/* calculate 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 left plane */
	t = sqrtf(frustum[1][0]*frustum[1][0]
		+ frustum[1][1]*frustum[1][1]
		+ frustum[1][2]*frustum[1][2]);
	frustum[1][0] /= t;
	frustum[1][1] /= t;
	frustum[1][2] /= t;
	frustum[1][3] /= t;

	/* calculate 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 bottom plane */
	t = sqrtf(frustum[2][0]*frustum[2][0]
		+ frustum[2][1]*frustum[2][1]
		+ frustum[2][2]*frustum[2][2]);
	frustum[2][0] /= t;
	frustum[2][1] /= t;
	frustum[2][2] /= t;
	frustum[2][3] /= t;

	/* calculate 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 top plane */
	t = sqrtf(frustum[3][0]*frustum[3][0]
		+ frustum[3][1]*frustum[3][1]
		+ frustum[3][2]*frustum[3][2]);
	frustum[3][0] /= t;
	frustum[3][1] /= t;
	frustum[3][2] /= t;
	frustum[3][3] /= t;

	/* calculate 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 far plane */
	t = sqrtf(frustum[4][0]*frustum[4][0]
		+ frustum[4][1]*frustum[4][1]
		+ frustum[4][2]*frustum[4][2]);
	frustum[4][0] /= t;
	frustum[4][1] /= t;
	frustum[4][2] /= t;
	frustum[4][3] /= t;

	/* calculate 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 near plane */
	t = sqrtf(frustum[5][0]*frustum[5][0]
		+ frustum[5][1]*frustum[5][1]
		+ frustum[5][2]*frustum[5][2]);
	frustum[5][0] /= t;
	frustum[5][1] /= t;
	frustum[5][2] /= t;
	frustum[5][3] /= t;
}

int FRUSTUM::
	CubeInFrustum(float x, float y, float z, float size) {
	int c, c2;

	c2 = 0;
	for(int i=0; i<6; i++) {
		c=0;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y-size) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y-size) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y+size) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y+size) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y-size) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y-size) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y+size) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y+size) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(c==0)
			return 0;
		if(c==8)
			c2++;
	}
	if(c2>=6)
		return 2;
	else
		return 1;
}

int FRUSTUM::
	CubeInFrustum(float x, float y, float z, float size, float height) {
	int c, c2;

	c2 = 0;
	for(int i=0; i<6; i++) {
		c=0;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y-height) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y-height) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y+height) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y+height) + frustum[i][2] * (z-size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y-height) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y-height) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x-size) + frustum[i][1] * (y+height) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(frustum[i][0] * (x+size) + frustum[i][1] * (y+height) + frustum[i][2] * (z+size) + frustum[i][3] > 0)
			c++;
		if(c==0)
			return 0;
		if(c==8)
			c2++;
	}
	if(c2>=6)
		return 2;
	else
		return 1;
}

int FRUSTUM::
	SphereInFrustum(float x, float y, float z, float radius) {
	int  c2;

	c2 = 0;
	for(int i=0; i<6; i++) {
		if(frustum[i][0] * x + frustum[i][1] * y + frustum[i][2] * z + frustum[i][3] > -1*radius)
			c2++;
		else
			return 0;
	}
	if(c2>=6)
		return 2;
	else
		return 1;
}