Added shaders for OpenGL ES

resources/shaders/ES/wireframe.fs

@@ -0,0 +1,19 @@
+#version 100
+#extension GL_OES_standard_derivatives : enable
+
+// see for reference: https://stackoverflow.com/questions/7361582/opengl-debugging-single-pass-wireframe-rendering
+
+precision highp float;
+
+uniform vec4 uniform_color;
+
+varying vec3 barycentric;
+
+void main()
+{
+    float min_dist = min(min(barycentric.x, barycentric.y), barycentric.z);
+	if (min_dist > 0.5 * fwidth(min_dist))
+		discard;
+	
+    gl_FragColor = uniform_color;
+}