40 lines
1.0 KiB
GLSL
40 lines
1.0 KiB
GLSL
#version 300 es
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precision highp float;
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in vec2 v_texCoord;
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in vec4 v_color;
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uniform sampler2D u_texture;
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uniform float u_opacity;
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uniform float u_sdfThreshold;
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uniform float u_sdfSmoothness;
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uniform vec2 u_textureSize;
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out vec4 fragColor;
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void main() {
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// 采样 SDF 纹理（SDF 值存储在 alpha 通道，范围 0-255 已映射到 0-1）
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float sdfValue = texture(u_texture, v_texCoord).a;
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// 使用 fwidth 计算屏幕空间的变化率
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float fw = fwidth(sdfValue);
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// 平衡的抗锯齿：根据屏幕空间变化率调整平滑范围
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// 在放大时更平滑，缩小时更锐利
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float smoothRange = max(u_sdfSmoothness, fw * 0.5);
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// 使用 smoothstep 进行抗锯齿
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float alpha = smoothstep(u_sdfThreshold - smoothRange,
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u_sdfThreshold + smoothRange,
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sdfValue);
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// 应用颜色和透明度
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fragColor = v_color;
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fragColor.a *= alpha * u_opacity;
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// 丢弃完全透明的像素
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if (fragColor.a < 0.001) {
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discard;
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}
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}
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