add mc_kuwahara_shader

mc_kuwahara_shader/shaders/gbuffers_terrain.fsh

@@ -0,0 +1,20 @@
+#version 150
+
+/* DRAWBUFFERS:0 */
+
+uniform sampler2D gtexture;
+uniform sampler2D lightmap;
+
+in vec2 texCoord;
+in vec4 tintColor;
+in vec2 lightCoord;
+
+out vec4 fragColor;
+
+void main() {
+    vec4 color = texture(gtexture, texCoord);
+    if (color.a < 0.1) discard;
+    color *= tintColor;
+    color.rgb *= texture(lightmap, lightCoord).rgb;
+    fragColor = color;
+}