Basic Harfbuzz support and use MSDGen with Skia

Sandbox/content/Shaders/msdfShader.hlsl

@@ -35,11 +35,34 @@ PS_Input VS(VS_Input input)
     return output;
 }
 
+/*
+in vec2 texCoord;
+out vec4 color;
+uniform sampler2D msdf;
+uniform vec4 bgColor;
+uniform vec4 fgColor;
+
 float median(float r, float g, float b) {
     return max(min(r, g), min(max(r, g), b));
 }
 
-float ScreenPxRange(float2 texcoord) {
+void main() {
+    vec3 msd = texture(msdf, texCoord).rgb;
+    float sd = median(msd.r, msd.g, msd.b);
+    float screenPxDistance = screenPxRange()*(sd - 0.5);
+    float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
+    color = mix(bgColor, fgColor, opacity);
+}
+*/
+
+
+float median(float r, float g, float b)
+{
+    return max(min(r, g), min(max(r, g), b));
+}
+
+float ScreenPxRange(float2 texcoord)
+{
     float2 screenTexSize = 1.0f / fwidth(texcoord);
     return max(0.5f * dot(UnitRange, screenTexSize), 1.0f);
 }
@@ -54,4 +77,17 @@ float4 PS(PS_Input input) : SV_Target0
     return float4(input.Color.rgb, opacity * input.Color.a);
 }
 
+/*
+// 2D
+float4 PS(PS_Input input) : SV_Target0
+{
+    float3 msd = Texture.Sample(Sampler, input.TexCoord).rgb;
+    float sd = median(msd.r, msd.g, msd.b);
+    float screenPxDistance = screenPixelRange*(sd - 0.5);
+    float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
+
+    return float4(input.Color.rgb, opacity * input.Color.a);
+}
+*/
+
 #effect[VS=VS, PS=PS]