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67 lines
1.9 KiB
GLSL
67 lines
1.9 KiB
GLSL
#ifdef GL_OES_standard_derivatives
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#extension GL_OES_standard_derivatives : enable
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#endif
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uniform vec4 color;
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float getPointOnLine(vec2 p0, vec2 p1, float x)
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{
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float slope = (p0.y - p1.y) / (p0.x - p1.x);
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return slope * (x - p0.x) + p0.y;
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}
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czm_material czm_getMaterial(czm_materialInput materialInput)
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{
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czm_material material = czm_getDefaultMaterial(materialInput);
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vec2 st = materialInput.st;
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#ifdef GL_OES_standard_derivatives
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float base = 1.0 - abs(fwidth(st.s)) * 10.0 * czm_pixelRatio;
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#else
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float base = 0.975; // 2.5% of the line will be the arrow head
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#endif
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vec2 center = vec2(1.0, 0.5);
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float ptOnUpperLine = getPointOnLine(vec2(base, 1.0), center, st.s);
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float ptOnLowerLine = getPointOnLine(vec2(base, 0.0), center, st.s);
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float halfWidth = 0.15;
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float s = step(0.5 - halfWidth, st.t);
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s *= 1.0 - step(0.5 + halfWidth, st.t);
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s *= 1.0 - step(base, st.s);
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float t = step(base, materialInput.st.s);
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t *= 1.0 - step(ptOnUpperLine, st.t);
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t *= step(ptOnLowerLine, st.t);
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// Find the distance from the closest separator (region between two colors)
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float dist;
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if (st.s < base)
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{
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float d1 = abs(st.t - (0.5 - halfWidth));
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float d2 = abs(st.t - (0.5 + halfWidth));
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dist = min(d1, d2);
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}
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else
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{
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float d1 = czm_infinity;
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if (st.t < 0.5 - halfWidth && st.t > 0.5 + halfWidth)
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{
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d1 = abs(st.s - base);
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}
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float d2 = abs(st.t - ptOnUpperLine);
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float d3 = abs(st.t - ptOnLowerLine);
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dist = min(min(d1, d2), d3);
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}
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vec4 outsideColor = vec4(0.0);
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vec4 currentColor = mix(outsideColor, color, clamp(s + t, 0.0, 1.0));
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vec4 outColor = czm_antialias(outsideColor, color, currentColor, dist);
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outColor = czm_gammaCorrect(outColor);
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material.diffuse = outColor.rgb;
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material.alpha = outColor.a;
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return material;
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}
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