Simon Schneegans
33 lines
1.6 KiB
GLSL
33 lines
1.6 KiB
GLSL
// This method returns a mask which smoothly transitions towards zero when approaching
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// the window's borders. There is a variant which takes the transition area width in
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// pixels and one which takes this as a percentage.
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float getEdgeMask(vec2 uv, vec2 maxUV, float fadeWidth) {
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float mask = 1.0;
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mask *= smoothstep(0, 1, clamp(uv.x / fadeWidth, 0, 1));
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mask *= smoothstep(0, 1, clamp(uv.y / fadeWidth, 0, 1));
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mask *= smoothstep(0, 1, clamp((maxUV.x - uv.x) / fadeWidth, 0, 1));
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mask *= smoothstep(0, 1, clamp((maxUV.y - uv.y) / fadeWidth, 0, 1));
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return mask;
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}
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// Returns an edge mask which fades to zero at the boundaries of the actor. The width of
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// the fade zone is given in pixels. This uses the standard uniforms uSize and uPadding.
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// This means that the fading zone is not actually at the actors boundaries but at the
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// position of the window border in the texture.
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// The offset paramter controls whether the fading is placed inside the window borders
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// (offset = 0), ontop the window borders (offset = 0.5) or outside the window borders
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// (offset = 1).
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float getAbsoluteEdgeMask(float fadePixels, float offset) {
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float padding = max(0, uPadding - fadePixels * offset);
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vec2 uv = cogl_tex_coord_in[0].st * uSize - padding;
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return getEdgeMask(uv, uSize - 2.0 * padding, fadePixels);
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}
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// Returns an edge mask which fades to zero at the boundaries of the actor. The width of
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// the fade zone is given relative to the actor size. This neither uses uSize and
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// uPadding.
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float getRelativeEdgeMask(float fadeAmount) {
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vec2 uv = cogl_tex_coord_in[0].st;
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return getEdgeMask(uv, vec2(1.0), fadeAmount);
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} |