Circle map style rendering (#202) #122

vtm/resources/assets/shaders/circle.glsl

@@ -0,0 +1,30 @@
+#ifdef GLES
+precision highp float;
+#endif
+uniform mat4 u_mvp;
+uniform float u_radius;
+uniform vec2 u_screen;
+attribute vec2 a_pos;
+varying vec2 v_tex;
+
+void
+main(){
+  gl_Position = u_mvp * vec4(a_pos, 0.0, 1.0);
+  v_tex = a_pos;
+}
+
+$$
+
+#ifdef GLES
+precision highp float;
+#endif
+varying vec2 v_tex;
+uniform float u_radius;
+uniform vec4 u_color;
+uniform vec2 u_screen;
+
+void
+main(){
+  float len = 1.0 - length(v_tex - u_screen);
+  gl_FragColor = u_color * smoothstep(0.0, u_radius, len);
+}