forked from AuroraMiddleware/gtk
82 lines
2.2 KiB
GLSL
82 lines
2.2 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[8 * 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[8];
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_OUT_ float color_offsets[8];
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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].r = u_color_stops[(i * 5) + 1];
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color_stops[i].g = u_color_stops[(i * 5) + 2];
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color_stops[i].b = u_color_stops[(i * 5) + 3];
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color_stops[i].a = 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[8];
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_IN_ float color_offsets[8];
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vec4 fragCoord() {
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vec4 f = gl_FragCoord;
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f.x += u_viewport.x;
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f.y = (u_viewport.y + u_viewport.w) - f.y;
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return f;
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}
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void main() {
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// Position relative to startPoint
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vec2 pos = fragCoord().xy - 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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/* Pre-multiply */
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color.rgb *= color.a;
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setOutputColor(color * u_alpha);
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}
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