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#include "stdafx.h"
#include "..\Minecraft.World\FloatBuffer.h"
#include "Frustum.h"
Frustum *Frustum::frustum = new Frustum();
Frustum::Frustum()
{
_proj = MemoryTracker::createFloatBuffer(16);
_modl = MemoryTracker::createFloatBuffer(16);
_clip = MemoryTracker::createFloatBuffer(16);
}
Frustum::~Frustum()
{
delete _proj;
delete _modl;
delete _clip;
}
FrustumData *Frustum::getFrustum()
{
frustum->calculateFrustum();
return frustum;
}
///////////////////////////////// NORMALIZE PLANE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
/////
///// This normalizes a plane (A side) from a given frustum.
/////
///////////////////////////////// NORMALIZE PLANE \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\*
void Frustum::normalizePlane(float **frustum, int side)
{
float magnitude = (float) sqrt(frustum[side][A] * frustum[side][A] + frustum[side][B] * frustum[side][B] + frustum[side][C] * frustum[side][C]);
// Then we divide the plane's values by it's magnitude.
// This makes it easier to work with.
frustum[side][A] /= magnitude;
frustum[side][B] /= magnitude;
frustum[side][C] /= magnitude;
frustum[side][D] /= magnitude;
}
void Frustum::calculateFrustum()
{
_proj->clear();
_modl->clear();
_clip->clear();
// glGetFloatv() is used to extract information about our OpenGL world.
// Below, we pass in GL_PROJECTION_MATRIX to abstract our projection matrix.
// It then stores the matrix into an array of [16].
glGetFloat(GL_PROJECTION_MATRIX, _proj);
// By passing in GL_MODELVIEW_MATRIX, we can abstract our model view matrix.
// This also stores it in an array of [16].
glGetFloat(GL_MODELVIEW_MATRIX, _modl);
_proj->flip()->limit(16);
_proj->get(&proj);
_modl->flip()->limit(16);
_modl->get(&modl);
// Now that we have our modelview and projection matrix, if we combine these 2 matrices,
// it will give us our clipping planes. To combine 2 matrices, we multiply them.
clip[0] = modl[0] * proj[0] + modl[1] * proj[4] + modl[2] * proj[8] + modl[3] * proj[12];
clip[1] = modl[0] * proj[1] + modl[1] * proj[5] + modl[2] * proj[9] + modl[3] * proj[13];
clip[2] = modl[0] * proj[2] + modl[1] * proj[6] + modl[2] * proj[10] + modl[3] * proj[14];
clip[3] = modl[0] * proj[3] + modl[1] * proj[7] + modl[2] * proj[11] + modl[3] * proj[15];
clip[4] = modl[4] * proj[0] + modl[5] * proj[4] + modl[6] * proj[8] + modl[7] * proj[12];
clip[5] = modl[4] * proj[1] + modl[5] * proj[5] + modl[6] * proj[9] + modl[7] * proj[13];
clip[6] = modl[4] * proj[2] + modl[5] * proj[6] + modl[6] * proj[10] + modl[7] * proj[14];
clip[7] = modl[4] * proj[3] + modl[5] * proj[7] + modl[6] * proj[11] + modl[7] * proj[15];
clip[8] = modl[8] * proj[0] + modl[9] * proj[4] + modl[10] * proj[8] + modl[11] * proj[12];
clip[9] = modl[8] * proj[1] + modl[9] * proj[5] + modl[10] * proj[9] + modl[11] * proj[13];
clip[10] = modl[8] * proj[2] + modl[9] * proj[6] + modl[10] * proj[10] + modl[11] * proj[14];
clip[11] = modl[8] * proj[3] + modl[9] * proj[7] + modl[10] * proj[11] + modl[11] * proj[15];
clip[12] = modl[12] * proj[0] + modl[13] * proj[4] + modl[14] * proj[8] + modl[15] * proj[12];
clip[13] = modl[12] * proj[1] + modl[13] * proj[5] + modl[14] * proj[9] + modl[15] * proj[13];
clip[14] = modl[12] * proj[2] + modl[13] * proj[6] + modl[14] * proj[10] + modl[15] * proj[14];
clip[15] = modl[12] * proj[3] + modl[13] * proj[7] + modl[14] * proj[11] + modl[15] * proj[15];
// Now we actually want to get the sides of the frustum. To do this we take
// the clipping planes we received above and extract the sides from them.
// This will extract the RIGHT side of the frustum
m_Frustum[RIGHT][A] = clip[3] - clip[0];
m_Frustum[RIGHT][B] = clip[7] - clip[4];
m_Frustum[RIGHT][C] = clip[11] - clip[8];
m_Frustum[RIGHT][D] = clip[15] - clip[12];
// Now that we have a normal (A,B,C) and a distance (D) to the plane,
// we want to normalize that normal and distance.
// Normalize the RIGHT side
normalizePlane(m_Frustum, RIGHT);
// This will extract the LEFT side of the frustum
m_Frustum[LEFT][A] = clip[3] + clip[0];
m_Frustum[LEFT][B] = clip[7] + clip[4];
m_Frustum[LEFT][C] = clip[11] + clip[8];
m_Frustum[LEFT][D] = clip[15] + clip[12];
// Normalize the LEFT side
normalizePlane(m_Frustum, LEFT);
// This will extract the BOTTOM side of the frustum
m_Frustum[BOTTOM][A] = clip[3] + clip[1];
m_Frustum[BOTTOM][B] = clip[7] + clip[5];
m_Frustum[BOTTOM][C] = clip[11] + clip[9];
m_Frustum[BOTTOM][D] = clip[15] + clip[13];
// Normalize the BOTTOM side
normalizePlane(m_Frustum, BOTTOM);
// This will extract the TOP side of the frustum
m_Frustum[TOP][A] = clip[3] - clip[1];
m_Frustum[TOP][B] = clip[7] - clip[5];
m_Frustum[TOP][C] = clip[11] - clip[9];
m_Frustum[TOP][D] = clip[15] - clip[13];
// Normalize the TOP side
normalizePlane(m_Frustum, TOP);
// This will extract the BACK side of the frustum
m_Frustum[BACK][A] = clip[3] - clip[2];
m_Frustum[BACK][B] = clip[7] - clip[6];
m_Frustum[BACK][C] = clip[11] - clip[10];
m_Frustum[BACK][D] = clip[15] - clip[14];
// Normalize the BACK side
normalizePlane(m_Frustum, BACK);
// This will extract the FRONT side of the frustum
m_Frustum[FRONT][A] = clip[3] + clip[2];
m_Frustum[FRONT][B] = clip[7] + clip[6];
m_Frustum[FRONT][C] = clip[11] + clip[10];
m_Frustum[FRONT][D] = clip[15] + clip[14];
// Normalize the FRONT side
normalizePlane(m_Frustum, FRONT);
}
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