SinglePass Lighting: support two sided lighting

 - also added test case with both regular per pixel lighting and bump mapping
 - NOTE: two sided lighting is not supported with vertex lighting

jme3-core/src/main/resources/Common/MatDefs/Light/SPLighting.frag

@@ -74,6 +74,12 @@ uniform float m_Shininess;
 void main(){
     #ifdef NORMALMAP   
         mat3 tbnMat = mat3(normalize(vTangent.xyz) , normalize(vBinormal.xyz) , normalize(vNormal.xyz));
+
+        if (!gl_FrontFacing)
+        {
+            tbnMat[2] = -tbnMat[2];
+        }
+
         vec3 viewDir = normalize(-vPos.xyz * tbnMat);
     #else
         vec3 viewDir = normalize(-vPos.xyz);
@@ -133,7 +139,12 @@ void main(){
       //for more explanation.
       vec3 normal = normalize((normalHeight.xyz * vec3(2.0,-2.0,2.0) - vec3(1.0,-1.0,1.0)));
     #elif !defined(VERTEX_LIGHTING)
-      vec3 normal = normalize(vNormal);            
+      vec3 normal = normalize(vNormal); 
+
+      if (!gl_FrontFacing)
+      {
+          normal = -normal;
+      }           
     #endif
 
     #ifdef SPECULARMAP

jme3-examples/src/main/java/jme3test/light/TestTwoSideLighting.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2009-2015 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package jme3test.light;
+
+import com.jme3.app.SimpleApplication;
+import com.jme3.light.DirectionalLight;
+import com.jme3.light.PointLight;
+import com.jme3.material.Material;
+import com.jme3.material.RenderState;
+import com.jme3.material.TechniqueDef;
+import com.jme3.math.ColorRGBA;
+import com.jme3.math.FastMath;
+import com.jme3.math.Quaternion;
+import com.jme3.math.Vector3f;
+import com.jme3.scene.Geometry;
+import com.jme3.scene.shape.Quad;
+import com.jme3.scene.shape.Sphere;
+import com.jme3.util.MaterialDebugAppState;
+import com.jme3.util.TangentBinormalGenerator;
+
+/**
+ * Checks two sided lighting capability.
+ * 
+ * @author Kirill Vainer
+ */
+public class TestTwoSideLighting extends SimpleApplication {
+
+    float angle;
+    PointLight pl;
+    Geometry lightMdl;
+
+    public static void main(String[] args){
+        TestTwoSideLighting app = new TestTwoSideLighting();
+        app.start();
+    }
+
+    @Override
+    public void simpleInitApp() {
+        // Two-sided lighting requires single pass.
+        renderManager.setPreferredLightMode(TechniqueDef.LightMode.SinglePass);
+        renderManager.setSinglePassLightBatchSize(4);
+        
+        cam.setLocation(new Vector3f(5.936224f, 3.3759952f, -3.3202777f));
+        cam.setRotation(new Quaternion(0.16265652f, -0.4811838f, 0.09137692f, 0.8565368f));
+        
+        Geometry quadGeom = new Geometry("quad", new Quad(1, 1));
+        quadGeom.move(1, 0, 0);
+        Material mat1 = assetManager.loadMaterial("Textures/BumpMapTest/SimpleBump.j3m");
+        
+        // Display both front and back faces.
+        mat1.getAdditionalRenderState().setFaceCullMode(RenderState.FaceCullMode.Off);
+        
+        quadGeom.setMaterial(mat1);
+        // SimpleBump material requires tangents.
+        TangentBinormalGenerator.generate(quadGeom);
+        rootNode.attachChild(quadGeom);
+        
+        Geometry teapot = (Geometry) assetManager.loadModel("Models/Teapot/Teapot.obj");
+        teapot.move(-1, 0, 0);
+        teapot.setLocalScale(2f);
+        Material mat2 = new Material(assetManager, "Common/MatDefs/Light/Lighting.j3md");
+        mat2.setFloat("Shininess", 25);
+        mat2.setBoolean("UseMaterialColors", true);
+        mat2.setColor("Ambient",  ColorRGBA.Black);
+        mat2.setColor("Diffuse",  ColorRGBA.Gray);
+        mat2.setColor("Specular", ColorRGBA.Gray);
+        
+        // Only display backfaces.
+        mat2.getAdditionalRenderState().setFaceCullMode(RenderState.FaceCullMode.Front);
+        
+        teapot.setMaterial(mat2);
+        rootNode.attachChild(teapot);
+
+        lightMdl = new Geometry("Light", new Sphere(10, 10, 0.1f));
+        lightMdl.setMaterial(assetManager.loadMaterial("Common/Materials/RedColor.j3m"));
+        lightMdl.getMesh().setStatic();
+        rootNode.attachChild(lightMdl);
+
+        pl = new PointLight();
+        pl.setColor(ColorRGBA.White);
+        pl.setRadius(4f);
+        rootNode.addLight(pl);
+    }
+
+    @Override
+    public void simpleUpdate(float tpf){
+        angle += tpf;
+        angle %= FastMath.TWO_PI;
+        
+        pl.setPosition(new Vector3f(FastMath.cos(angle) * 3f, 0.5f, FastMath.sin(angle) * 3f));
+        lightMdl.setLocalTranslation(pl.getPosition());
+    }
+
+}