forked from AuroraMiddleware/gtk
70 lines
2.0 KiB
GLSL
70 lines
2.0 KiB
GLSL
// VERTEX_SHADER
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uniform vec2 u_center;
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uniform float u_rotation;
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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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const float PI = 3.1415926535897932384626433832795;
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_OUT_ vec2 center;
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_OUT_ float rotation;
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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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// The -90 is because conics point to the top by default
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rotation = mod (u_rotation - 90, 360.0);
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if (rotation < 0)
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rotation += 360.0;
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rotation = PI / 180.0 * rotation;
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center = (u_modelview * vec4(u_center, 0, 1)).xy;
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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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const float PI = 3.1415926535897932384626433832795;
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_IN_ vec2 center;
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_IN_ float rotation;
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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 center
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vec2 pos = gsk_get_frag_coord() - center;
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// direction of point in range [-PI, PI]
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float angle = atan (pos.y, pos.x);
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// rotate, it's now [-2 * PI, PI]
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angle -= rotation;
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// fract() does the modulo here, so now we have progress
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// into the current conic
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float offset = fract (angle / 2 / PI + 2);
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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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