// Implicit uniforms: // uniform vec2 PREFIX(offset); // uniform vec2 PREFIX(scale); // // uniform vec2 PREFIX(normalized_coords_to_texels); // uniform vec2 PREFIX(offset_bottomleft); // uniform vec2 PREFIX(offset_topright); vec4 FUNCNAME(vec2 tc) { tc -= PREFIX(offset); tc *= PREFIX(scale); vec2 tc_texels = tc * PREFIX(normalized_coords_to_texels); vec2 coverage_bottomleft = clamp(tc_texels + PREFIX(offset_bottomleft), 0.0f, 1.0f); vec2 coverare_topright = clamp(PREFIX(offset_topright) - tc_texels, 0.0f, 1.0f); vec2 coverage_both = coverage_bottomleft * coverare_topright; float coverage = coverage_both.x * coverage_both.y; if (coverage <= 0.0f) { // Short-circuit in case the underlying function is expensive to call. return PREFIX(border_color); } else { return mix(PREFIX(border_color), INPUT(tc), coverage); } }