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/* simple depth reconstruction, see http://www.derschmale.com/2014/01/26/reconstructing-positions-from-the-depth-buffer
* we change the factors from the article to fit the OpennGL model. */
#ifdef PERSP_MATRIX
/* perspective camera code */
vec3 get_view_space_from_depth(in vec2 uvcoords, in vec3 viewvec_origin, in vec3 viewvec_diff, in float depth)
{
float d = 2.0 * depth - 1.0;
float zview = -gl_ProjectionMatrix[3][2] / (d + gl_ProjectionMatrix[2][2]);
return zview * (viewvec_origin + vec3(uvcoords, 0.0) * viewvec_diff);
}
vec4 get_view_space_z_from_depth(in vec4 near, in vec4 range, in vec4 depth)
{
vec4 d = 2.0 * depth - vec4(1.0);
/* return positive value, so sign differs! */
return vec4(gl_ProjectionMatrix[3][2]) / (d + vec4(gl_ProjectionMatrix[2][2]));
}
#else
/* orthographic camera code */
vec3 get_view_space_from_depth(in vec2 uvcoords, in vec3 viewvec_origin, in vec3 viewvec_diff, in float depth)
{
vec3 offset = vec3(uvcoords, depth);
return vec3(viewvec_origin + offset * viewvec_diff);
}
vec4 get_view_space_z_from_depth(in vec4 near, in vec4 range, in vec4 depth)
{
return -(near + depth * range);
}
#endif
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