29 lines
815 B
Text
29 lines
815 B
Text
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#extension GL_OES_standard_derivatives : enable
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#ifdef GL_ES
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precision mediump float;
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#endif
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varying vec2 v_texCoord;
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uniform sampler2D msdf;
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uniform vec4 u_bgColor;
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uniform vec4 u_fgColor;
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uniform float u_distanceRange;
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uniform float u_glyphSize;
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uniform vec2 u_resolution;
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uniform vec4 u_viewbox;
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float median(float r, float g, float b) {
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return max(min(r, g), min(max(r, g), b));
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}
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void main() {
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float scale = u_distanceRange / u_glyphSize * u_resolution.y / u_viewbox.w;
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vec3 msd = texture2D(msdf, v_texCoord).rgb;
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float sd = median(msd.r, msd.g, msd.b);
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float screenPxRange = max(u_distanceRange, scale);
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float screenPxDistance = screenPxRange*(sd - 0.5);
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float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
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gl_FragColor = vec4(u_fgColor.rgb, u_fgColor.a * opacity);
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}
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