Added flipping workaround to RTT example.

Please note that render target must be power-of-2 sized for this trick to work. Other option would be to change directly UVs in the geometry (though that would make it harder to swap image vs render target as texture or to share geometry between objects using materials with images vs render targets).

Fixes #2164

examples/webgl_rtt.html

@@ -82,6 +82,18 @@
 
 		</script>
 
+		<script id="vertexShaderFlip" type="x-shader/x-vertex">
+
+			varying vec2 vUv;
+
+			void main() {
+
+				vUv = vec2( uv.x, 1.0 - uv.y );
+				gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
+
+			}
+
+		</script>
 
 		<script>
 
@@ -132,7 +144,9 @@
 				light.position.set( 0, 0, -1 ).normalize();
 				sceneRTT.add( light );
 
-				rtTexture = new THREE.WebGLRenderTarget( window.innerWidth, window.innerHeight, { minFilter: THREE.LinearFilter, magFilter: THREE.NearestFilter, format: THREE.RGBFormat } );
+				rtTexture = new THREE.WebGLRenderTarget( 1024, 1024, { minFilter: THREE.LinearMipMapLinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBFormat } );
+				rtTexture.wrapS = rtTexture.wrapT = THREE.RepeatWrapping;
+				rtTexture.repeat.set( 1, -1 );
 
 				material = new THREE.ShaderMaterial( {
 
@@ -145,7 +159,7 @@
 				var materialScreen = new THREE.ShaderMaterial( {
 
 					uniforms: { tDiffuse: { type: "t", value: 0, texture: rtTexture } },
-					vertexShader: document.getElementById( 'vertexShader' ).textContent,
+					vertexShader: document.getElementById( 'vertexShaderFlip' ).textContent,
 					fragmentShader: document.getElementById( 'fragment_shader_screen' ).textContent,
 
 					depthWrite: false