47 lines
1.2 KiB
GLSL
47 lines
1.2 KiB
GLSL
#version 150 compatibility
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uniform int culling_mode;
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uniform int map_color_to_material;
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uniform int illumination_mode;
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int surface_side_handling(in vec3 position, inout vec3 normal, inout vec4 color)
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{
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// sign of dot product between normal and view vector tells us side that we see
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float sign_indicator = dot(normal, position);
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int side = (sign_indicator < 0.0) ? 1 : 0;
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// perform face culling
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switch (culling_mode) {
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case 1: // backface culling
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if (sign_indicator > 0.0) {
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return -1;
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}
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break;
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case 2: // frontface culling
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if (sign_indicator < 0.0) {
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return -1;
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}
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break;
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}
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// based on illumination mode and side, overwrite color with material color if needed, and overwrite normal with negated normal if needed
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if (illumination_mode > 0) {
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// negate normal for back faces in double sided illumination
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if (illumination_mode == 2 && side == 0) {
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normal = -normal;
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}
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// overwrite color with diffuse material color if no color mapping turned on
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if (side == 1) {
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if ((map_color_to_material & 1) == 0) {
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color = gl_FrontMaterial.diffuse;
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}
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}
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else {
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if ((map_color_to_material & 2) == 0) {
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color = gl_BackMaterial.diffuse;
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}
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}
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}
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return side;
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}
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