offsetmapping.h

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vec2 offsetmap(sampler2D normtex, vec2 base, vec3 eyevector)
{
#if !defined(OFFSETMAPPING_SCALE)
        #define OFFSETMAPPING_SCALE 1.0
#endif
        if (false)//(RELIEFMAPPING)
        {
                float i, f;
                vec3 OffsetVector = vec3(normalize(eyevector.xyz).xy * cvar_r_glsl_offsetmapping_scale * OFFSETMAPPING_SCALE * vec2(-1.0, 1.0), -1.0);
                vec3 RT = vec3(vec2(base.xy/* - OffsetVector.xy*OffsetMapping_Bias*/), 1.0);
                OffsetVector /= 10.0;
                for(i = 1.0; i < 10.0; ++i)
                        RT += OffsetVector *  step(texture2D(normtex, RT.xy).a, RT.z);
                for(i = 0.0, f = 1.0; i < 5.0; ++i, f *= 0.5)
                        RT += OffsetVector * (step(texture2D(normtex, RT.xy).a, RT.z) * f - 0.5 * f);
                return RT.xy;
        }
        else if (OFFSETMAPPING)
        {
                vec2 OffsetVector = normalize(eyevector).xy * cvar_r_glsl_offsetmapping_scale * OFFSETMAPPING_SCALE * vec2(-1.0, 1.0);
                vec2 tc = base;
                tc += OffsetVector;
                OffsetVector *= 0.333;
                tc -= OffsetVector * texture2D(normtex, tc).w;
                tc -= OffsetVector * texture2D(normtex, tc).w;
                tc -= OffsetVector * texture2D(normtex, tc).w;
                return tc;
        }
        return base;
}