void Frustum::InitFromGLState()
{
glGetDoublev(GL_PROJECTION_MATRIX, m_projMatrix.Data());
glGetDoublev(GL_MODELVIEW_MATRIX, m_modelMatrix.Data());
matrix4x4d m = matrix4x4d(m_projMatrix) * matrix4x4d(m_modelMatrix);
InitFromMatrix(m);
}
void GetFrustum(Plane planes[6])
{
GLdouble modelMatrix[16];
GLdouble projMatrix[16];
glGetDoublev (GL_MODELVIEW_MATRIX, modelMatrix);
glGetDoublev (GL_PROJECTION_MATRIX, projMatrix);
matrix4x4d m = matrix4x4d(projMatrix) * matrix4x4d(modelMatrix);
// Left clipping plane
planes[0].a = m[3] + m[0];
planes[0].b = m[7] + m[4];
planes[0].c = m[11] + m[8];
planes[0].d = m[15] + m[12];
// Right clipping plane
planes[1].a = m[3] - m[0];
planes[1].b = m[7] - m[4];
planes[1].c = m[11] - m[8];
planes[1].d = m[15] - m[12];
// Top clipping plane
planes[2].a = m[3] - m[1];
planes[2].b = m[7] - m[5];
planes[2].c = m[11] - m[9];
planes[2].d = m[15] - m[13];
// Bottom clipping plane
planes[3].a = m[3] + m[1];
planes[3].b = m[7] + m[5];
planes[3].c = m[11] + m[9];
planes[3].d = m[15] + m[13];
// Near clipping plane
planes[4].a = m[3] + m[2];
planes[4].b = m[7] + m[6];
planes[4].c = m[11] + m[10];
planes[4].d = m[15] + m[14];
// Far clipping plane
planes[5].a = m[3] + m[2];
planes[5].b = m[7] + m[6];
planes[5].c = m[11] + m[10];
planes[5].d = m[15] + m[14];
// Normalize the fuckers
for (int i=0; i<6; i++) {
double invlen;
invlen = 1.0 / sqrt(planes[i].a*planes[i].a + planes[i].b*planes[i].b + planes[i].c*planes[i].c);
planes[i].a *= invlen;
planes[i].b *= invlen;
planes[i].c *= invlen;
planes[i].d *= invlen;
}
}
