forked from AuroraMiddleware/gtk
71 lines
2.1 KiB
GLSL
71 lines
2.1 KiB
GLSL
// VERTEX_SHADER
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uniform vec2 u_start_point;
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uniform vec2 u_end_point;
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uniform float u_color_stops[6 * 5];
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uniform int u_num_color_stops;
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_OUT_ vec2 startPoint;
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_OUT_ vec2 endPoint;
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_OUT_ float maxDist;
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_OUT_ vec2 gradient;
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_OUT_ float gradientLength;
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_OUT_ vec4 color_stops[6];
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_OUT_ float color_offsets[6];
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void main() {
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gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
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startPoint = (u_modelview * vec4(u_start_point, 0, 1)).xy;
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endPoint = (u_modelview * vec4(u_end_point, 0, 1)).xy;
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maxDist = length(endPoint - startPoint);
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// Gradient direction
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gradient = endPoint - startPoint;
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gradientLength = length(gradient);
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for (int i = 0; i < u_num_color_stops; i ++) {
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color_offsets[i] = u_color_stops[(i * 5) + 0];
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color_stops[i] = gsk_premultiply(vec4(u_color_stops[(i * 5) + 1],
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u_color_stops[(i * 5) + 2],
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u_color_stops[(i * 5) + 3],
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u_color_stops[(i * 5) + 4]));
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}
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}
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// FRAGMENT_SHADER:
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#ifdef GSK_LEGACY
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uniform int u_num_color_stops;
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#else
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uniform highp int u_num_color_stops; // Why? Because it works like this.
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#endif
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_IN_ vec2 startPoint;
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_IN_ vec2 endPoint;
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_IN_ float maxDist;
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_IN_ vec2 gradient;
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_IN_ float gradientLength;
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_IN_ vec4 color_stops[6];
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_IN_ float color_offsets[6];
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void main() {
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// Position relative to startPoint
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vec2 pos = gsk_get_frag_coord() - startPoint;
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// Current pixel, projected onto the line between the start point and the end point
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// The projection will be relative to the start point!
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vec2 proj = (dot(gradient, pos) / (gradientLength * gradientLength)) * gradient;
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// Offset of the current pixel
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float offset = length(proj) / maxDist;
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vec4 color = color_stops[0];
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for (int i = 1; i < u_num_color_stops; i ++) {
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if (offset >= color_offsets[i - 1]) {
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float o = (offset - color_offsets[i - 1]) / (color_offsets[i] - color_offsets[i - 1]);
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color = mix(color_stops[i - 1], color_stops[i], clamp(o, 0.0, 1.0));
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}
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}
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gskSetOutputColor(color * u_alpha);
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}
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