frustum_t proj_frustum(const float4x4& proj, bool normalize_planes)
{
// Gil Gribb & Klaus Hartmann, assumed public domain
// http://www2.ravensoft.com/users/ggribb/plane%20extraction.pdf
// http://crazyjoke.free.fr/doc/3D/plane%20extraction.pdf
frustum_t f;
f[oCUBE_LEFT].x = proj[0][3] + proj[0][0];
f[oCUBE_LEFT].y = proj[1][3] + proj[1][0];
f[oCUBE_LEFT].z = proj[2][3] + proj[2][0];
f[oCUBE_LEFT].w = proj[3][3] + proj[3][0];
f[oCUBE_RIGHT].x = proj[0][3] - proj[0][0];
f[oCUBE_RIGHT].y = proj[1][3] - proj[1][0];
f[oCUBE_RIGHT].z = proj[2][3] - proj[2][0];
f[oCUBE_RIGHT].w = proj[3][3] - proj[3][0];
f[oCUBE_TOP].x = proj[0][3] - proj[0][1];
f[oCUBE_TOP].y = proj[1][3] - proj[1][1];
f[oCUBE_TOP].z = proj[2][3] - proj[2][1];
f[oCUBE_TOP].w = proj[3][3] - proj[3][1];
f[oCUBE_BOTTOM].x = proj[0][3] + proj[0][1];
f[oCUBE_BOTTOM].y = proj[1][3] + proj[1][1];
f[oCUBE_BOTTOM].z = proj[2][3] + proj[2][1];
f[oCUBE_BOTTOM].w = proj[3][3] + proj[3][1];
if (has_projection(proj))
{
f[oCUBE_NEAR].x = proj[0][2];
f[oCUBE_NEAR].y = proj[1][2];
f[oCUBE_NEAR].z = proj[2][2];
f[oCUBE_NEAR].w = proj[3][2];
}
else
{
f[oCUBE_NEAR].x = proj[0][3] + proj[0][2];
f[oCUBE_NEAR].y = proj[1][3] + proj[1][2];
f[oCUBE_NEAR].z = proj[2][3] + proj[2][2];
f[oCUBE_NEAR].w = proj[3][3] + proj[3][2];
}
f[oCUBE_FAR].x = proj[0][3] - proj[0][2];
f[oCUBE_FAR].y = proj[1][3] - proj[1][2];
f[oCUBE_FAR].z = proj[2][3] - proj[2][2];
f[oCUBE_FAR].w = proj[3][3] - proj[3][2];
if (normalize_planes)
for (auto& p : f)
p = normalize_plane(p);
return f;
}
/**
* @brief Update the frustum clipping planes.
*/
void RCamera::update_frustum() {
float pm[16];
float mvm[16];
/* get the projection matrix */
glGetFloatv(GL_PROJECTION_MATRIX, pm);
/* get the model view matrix */
glGetFloatv(GL_MODELVIEW_MATRIX, mvm);
matrix4 m_pm(pm);
matrix4 m_mvm(mvm);
matrix4 clip = m_mvm * m_pm;
clip.transpose();
frustum[0][0] = clip[3][0] - clip[0][0];
frustum[0][1] = clip[3][1] - clip[0][1];
frustum[0][2] = clip[3][2] - clip[0][2];
frustum[0][3] = clip[3][3] - clip[0][3];
normalize_plane(&frustum[0][0], &frustum[0][1], &frustum[0][2], &frustum[0][3]);
frustum[1][0] = clip[3][0] + clip[0][0];
frustum[1][1] = clip[3][1] + clip[0][1];
frustum[1][2] = clip[3][2] + clip[0][2];
frustum[1][3] = clip[3][3] + clip[0][3];
normalize_plane(&frustum[1][0], &frustum[1][1], &frustum[1][2], &frustum[1][3]);
frustum[2][0] = clip[3][0] + clip[1][0];
frustum[2][1] = clip[3][1] + clip[1][1];
frustum[2][2] = clip[3][2] + clip[1][2];
frustum[2][3] = clip[3][3] + clip[1][3];
normalize_plane(&frustum[2][0], &frustum[2][1], &frustum[2][2], &frustum[2][3]);
frustum[3][0] = clip[3][0] - clip[1][0];
frustum[3][1] = clip[3][1] - clip[1][1];
frustum[3][2] = clip[3][2] - clip[1][2];
frustum[3][3] = clip[3][3] - clip[1][3];
normalize_plane(&frustum[3][0], &frustum[3][1], &frustum[3][2], &frustum[3][3]);
frustum[4][0] = clip[3][0] - clip[2][0];
frustum[4][1] = clip[3][1] - clip[2][1];
frustum[4][2] = clip[3][2] - clip[2][2];
frustum[4][3] = clip[3][3] - clip[2][3];
normalize_plane(&frustum[4][0], &frustum[4][1], &frustum[4][2], &frustum[4][3]);
frustum[5][0] = clip[3][0] + clip[2][0];
frustum[5][1] = clip[3][1] + clip[2][1];
frustum[5][2] = clip[3][2] + clip[2][2];
frustum[5][3] = clip[3][3] + clip[2][3];
normalize_plane(&frustum[5][0], &frustum[5][1], &frustum[5][2], &frustum[5][3]);
}
