Merging r5975 through r6036 from trunk to ogl-es branch.

GLES drivers adapted, but only did make compile-tests.


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/branches/ogl-es@6038 dfc29bdd-3216-0410-991c-e03cc46cb475

media/pp_opengl.frag

@@ -0,0 +1,17 @@
+
+// Texture sampler
+uniform sampler2D TextureSampler;
+
+// TexCoords from vertex shader
+varying vec2 TexCoords;
+
+void main (void)
+{
+    // Texture is sampled at Texcoords using texture2D
+    vec4 Color = texture2D(TextureSampler, TexCoords);
+    
+    // Inverse the color to produce negative image effect
+    Color.rgb = 1.0 - Color.rgb;
+    
+    gl_FragColor = Color;
+}