89 lines
2.1 KiB
Text
89 lines
2.1 KiB
Text
shader_type canvas_item;
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render_mode blend_disabled;
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uniform sampler2D u_src_texture;
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uniform vec4 u_src_rect;
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uniform float u_opacity = 1.0;
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uniform int u_texture_index;
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uniform int u_mode; // 0: output index, 1: output weight
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uniform sampler2D u_index_map;
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uniform sampler2D u_weight_map;
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vec2 get_src_uv(vec2 screen_uv) {
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vec2 uv = u_src_rect.xy + screen_uv * u_src_rect.zw;
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return uv;
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}
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void fragment() {
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float brush_value = u_opacity * texture(TEXTURE, UV).r;
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vec2 src_uv = get_src_uv(SCREEN_UV);
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vec4 iv = texture(u_index_map, src_uv);
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vec4 wv = texture(u_weight_map, src_uv);
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float i[3] = {iv.r, iv.g, iv.b};
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float w[3] = {wv.r, wv.g, wv.b};
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if (brush_value > 0.0) {
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float texture_index_f = float(u_texture_index) / 255.0;
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int ci = u_texture_index % 3;
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float cm[3] = {-1.0, -1.0, -1.0};
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cm[ci] = 1.0;
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// Decompress third weight to make computations easier
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w[2] = 1.0 - w[0] - w[1];
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if (abs(i[ci] - texture_index_f) > 0.001) {
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// Pixel does not have our texture index,
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// transfer its weight to other components first
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if (w[ci] > brush_value) {
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w[0] -= cm[0] * brush_value;
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w[1] -= cm[1] * brush_value;
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w[2] -= cm[2] * brush_value;
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} else if (w[ci] >= 0.f) {
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w[ci] = 0.f;
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i[ci] = texture_index_f;
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}
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} else {
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// Pixel has our texture index, increase its weight
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if (w[ci] + brush_value < 1.f) {
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w[0] += cm[0] * brush_value;
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w[1] += cm[1] * brush_value;
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w[2] += cm[2] * brush_value;
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} else {
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// Pixel weight is full, we can set all components to the same index.
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// Need to nullify other weights because they would otherwise never reach
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// zero due to normalization
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w[0] = 0.0;
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w[1] = 0.0;
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w[2] = 0.0;
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w[ci] = 1.0;
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i[0] = texture_index_f;
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i[1] = texture_index_f;
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i[2] = texture_index_f;
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}
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}
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w[0] = clamp(w[0], 0.0, 1.0);
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w[1] = clamp(w[1], 0.0, 1.0);
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w[2] = clamp(w[2], 0.0, 1.0);
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// Renormalize
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float sum = w[0] + w[1] + w[2];
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w[0] /= sum;
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w[1] /= sum;
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w[2] /= sum;
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}
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if (u_mode == 0) {
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COLOR = vec4(i[0], i[1], i[2], 1.0);
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} else {
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COLOR = vec4(w[0], w[1], w[2], 1.0);
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}
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}
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