diff --git a/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.glsl b/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.glsl
index 1e469134c..ad12e3b0c 100644
--- a/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.glsl
+++ b/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.glsl
@@ -23,10 +23,12 @@ out vec4 color;
 
 void main(void)
 {
-  vec4 texel = fragment.color*texture(Diffuse,vert.texcoord);
+	vec4 texel = fragment.color*texture(Diffuse,vert.texcoord);
 	vec3 ct,cf;
 	float intensity,at,af;
-	
+	if (fragment.color.w==0)
+		discard;
+
 	intensity = 0.5+0.5*clamp( dot( normalize(normal),lightDir ), -1,1 );
 	
 	af = 1.0;
@@ -45,6 +47,5 @@ void main(void)
 	intensity = 0.7*intensity  + 0.3*intensity*visibility;
 	
 	cf = intensity*(vec3(1.0,1.0,1.0)-ambient)+ambient;
-		
 	color  = vec4(ct * cf, fragment.color.w);
 }
diff --git a/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.h b/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.h
index de316f9d7..c2a6a306f 100644
--- a/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.h
+++ b/examples/OpenGLWindow/Shaders/useShadowMapInstancingPS.h
@@ -17,10 +17,11 @@ static const char* useShadowMapInstancingFragmentShader= \
 "out vec4 color;\n"
 "void main(void)\n"
 "{\n"
-"  vec4 texel = fragment.color*texture(Diffuse,vert.texcoord);\n"
+"	vec4 texel = fragment.color*texture(Diffuse,vert.texcoord);\n"
 "	vec3 ct,cf;\n"
 "	float intensity,at,af;\n"
-"	\n"
+"	if (fragment.color.w==0)\n"
+"		discard;\n"
 "	intensity = 0.5+0.5*clamp( dot( normalize(normal),lightDir ), -1,1 );\n"
 "	\n"
 "	af = 1.0;\n"
@@ -37,7 +38,6 @@ static const char* useShadowMapInstancingFragmentShader= \
 "	intensity = 0.7*intensity  + 0.3*intensity*visibility;\n"
 "	\n"
 "	cf = intensity*(vec3(1.0,1.0,1.0)-ambient)+ambient;\n"
-"		\n"
 "	color  = vec4(ct * cf, fragment.color.w);\n"
 "}\n"
 ;
diff --git a/examples/OpenGLWindow/SimpleOpenGL2Renderer.cpp b/examples/OpenGLWindow/SimpleOpenGL2Renderer.cpp
index 564212f9d..13ca63eaf 100644
--- a/examples/OpenGLWindow/SimpleOpenGL2Renderer.cpp
+++ b/examples/OpenGLWindow/SimpleOpenGL2Renderer.cpp
@@ -26,7 +26,7 @@ B3_ATTRIBUTE_ALIGNED16(struct) SimpleGL2Instance
 	int m_shapeIndex;
 	b3Vector3 m_position;
 	b3Quaternion orn;
-	b3Vector3 m_rgbColor;
+	b3Vector4 m_rgbColor;
 	b3Vector3 m_scaling;
 	void clear()
 	{
@@ -182,6 +182,10 @@ void SimpleOpenGL2Renderer::drawOpenGL(int instanceIndex)
 	const SimpleGL2Instance& inst = *instPtr;
 	const SimpleGL2Shape* shape = m_data->m_shapes[inst.m_shapeIndex];
 
+	if (inst.m_rgbColor[3]==0)
+	{
+		return;
+	}
 
 	glPushMatrix(); 
 	b3Transform tr;
@@ -475,6 +479,8 @@ int SimpleOpenGL2Renderer::registerGraphicsInstance(int shapeIndex, const double
 	instance.m_rgbColor[0] = color[0];
 	instance.m_rgbColor[1] = color[1];
 	instance.m_rgbColor[2] = color[2];
+	instance.m_rgbColor[3] = color[3];
+
 	instance.m_scaling[0] = scaling[0];
 	instance.m_scaling[1] = scaling[1];
 	instance.m_scaling[2] = scaling[2];
@@ -496,6 +502,8 @@ int SimpleOpenGL2Renderer::registerGraphicsInstance(int shapeIndex, const float*
 	instance.m_rgbColor[0] = color[0];
 	instance.m_rgbColor[1] = color[1];
 	instance.m_rgbColor[2] = color[2];
+	instance.m_rgbColor[3] = color[3];
+
 	instance.m_scaling[0] = scaling[0];
 	instance.m_scaling[1] = scaling[1];
 	instance.m_scaling[2] = scaling[2];
diff --git a/examples/TinyRenderer/TinyRenderer.cpp b/examples/TinyRenderer/TinyRenderer.cpp
index 5a74d2ad8..db7bcbb35 100644
--- a/examples/TinyRenderer/TinyRenderer.cpp
+++ b/examples/TinyRenderer/TinyRenderer.cpp
@@ -487,7 +487,10 @@ void TinyRenderer::renderObject(TinyRenderObjectData& renderData)
     Model* model = renderData.m_model;
     if (0==model)
         return;
-    
+	//discard invisible objects (zero alpha)
+	if (model->getColorRGBA()[3]==0)
+		return;
+
     renderData.m_viewportMatrix = viewport(0,0,width, height);
     
     b3AlignedObjectArray<float>& zbuffer = renderData.m_depthBuffer;
@@ -506,7 +509,8 @@ void TinyRenderer::renderObject(TinyRenderObjectData& renderData)
 		btVector3 P(viewMatrixInv[0][3], viewMatrixInv[1][3], viewMatrixInv[2][3]);
         
         Shader shader(model, light_dir_local, light_color, modelViewMatrix, lightModelViewMatrix, renderData.m_projectionMatrix,renderData.m_modelMatrix, renderData.m_viewportMatrix, localScaling, model->getColorRGBA(), width, height, shadowBufferPtr, renderData.m_lightAmbientCoeff, renderData.m_lightDiffuseCoeff, renderData.m_lightSpecularCoeff);
-        
+       
+		
         for (int i=0; i<model->nfaces(); i++)
         {
 			B3_PROFILE("face");