渲染后端加入

shaders/sprite.frag

@@ -0,0 +1,21 @@
+#version 300 es
+precision highp float;
+in vec2 vTexCoord;
+in vec4 vColor;
+
+uniform sampler2D uTexture;
+uniform int uUseSDF;
+
+out vec4 fragColor;
+
+void main() {
+    if (uUseSDF == 1) {
+        float dist = texture(uTexture, vTexCoord).a;
+        float sd = (dist - 0.502) * 3.98;
+        float w = fwidth(sd);
+        float alpha = smoothstep(-w, w, sd);
+        fragColor = vec4(vColor.rgb, vColor.a * alpha);
+    } else {
+        fragColor = texture(uTexture, vTexCoord) * vColor;
+    }
+}