msdf font renderen

1 files changed, 29 insertions, 0 deletions

diff --git a/web/pw-visualizer/assets/shaders/frag/msdf.glsl b/web/pw-visualizer/assets/shaders/frag/msdf.glsl
new file mode 100644
index 0000000..5d2325b
--- /dev/null
+++ b/web/pw-visualizer/assets/shaders/frag/msdf.glsl
@@ -0,0 +1,29 @@
+#extension GL_OES_standard_derivatives : enable
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+varying vec2 v_texCoord;
+uniform sampler2D msdf;
+uniform vec4 u_bgColor;
+uniform vec4 u_fgColor;
+
+uniform float u_distanceRange;
+uniform float u_glyphSize;
+uniform vec2 u_resolution;
+uniform vec4 u_viewbox;
+
+float median(float r, float g, float b) {
+    return max(min(r, g), min(max(r, g), b));
+}
+
+void main() {
+    float scale = u_distanceRange / u_glyphSize * u_resolution.y / u_viewbox.w;
+
+    vec3 msd = texture2D(msdf, v_texCoord).rgb;
+    float sd = median(msd.r, msd.g, msd.b);
+    float screenPxRange = max(u_distanceRange, scale);
+    float screenPxDistance = screenPxRange*(sd - 0.5);
+    float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
+    gl_FragColor = vec4(u_fgColor.rgb, u_fgColor.a * opacity);
+}
\ No newline at end of file