Fix/Extend FBObject (API Change): plain init(GL), support multiple attachTexture2D(..) (MRT) w/ tex units

- plain initialization via init(GL)

- dedicated texture2D color buffer attachement attachTexture2D(..) w/ tex units (<GL_MAX_TEXTURE_UNITS),
  which may happen up to max GL_MAX_COLOR_ATTACHMENTS to support MRT (multiple render targets)

- more API doc

- FBO/MRT/GLSL unit test w/ using 2 shader (decompose / compose)

6 files changed, 482 insertions, 116 deletions

diff --git a/src/jogl/classes/com/jogamp/opengl/util/FBObject.java b/src/jogl/classes/com/jogamp/opengl/util/FBObject.java
index c57d4b057..0b6094128 100644
--- a/src/jogl/classes/com/jogamp/opengl/util/FBObject.java
+++ b/src/jogl/classes/com/jogamp/opengl/util/FBObject.java
@@ -37,16 +37,26 @@ package com.jogamp.opengl.util;
 import javax.media.opengl.*;
 
 public class FBObject {
+    static final int MAX_FBO_TEXTURES = 32; // just for our impl .. not the real 'max' FBO color attachments
+    private int[] fbo_tex_names;
+    private int[] fbo_tex_units;
+    private int fbo_tex_num;
+    private int colorattachment_num;
+
+    private boolean initialized;
     private int width, height;
-    private int fb, fbo_tex, depth_rb, stencil_rb, vStatus;
-    private int texInternalFormat, texDataFormat, texDataType;
+    private int fb, depth_rb, stencil_rb, vStatus;
     private boolean bound;
-        
+    
     public FBObject(int width, int height) {
+        this.fbo_tex_names = new int[MAX_FBO_TEXTURES];
+        this.fbo_tex_units = new int[MAX_FBO_TEXTURES];
+        this.fbo_tex_num = 0;
+        this.colorattachment_num = 0;
+        this.initialized = false;
         this.width = width;
         this.height = height;
         this.fb = 0;
-        this.fbo_tex = 0;
         this.depth_rb = 0;
         this.stencil_rb = 0;
         this.bound = false;
@@ -117,38 +127,6 @@ public class FBObject {
         }
     }
     
-    /**
-     * Initializes this FBO's instance with it's texture,
-     * selecting the texture data type and format automatically.
-     * 
-     * Leaves the FBO bound!
-     * 
-     * @param gl the current GL context
-     * @param magFilter if > 0 value for {@link GL#GL_TEXTURE_MAG_FILTER}
-     * @param minFilter if > 0 value for {@link GL#GL_TEXTURE_MIN_FILTER} 
-     * @param wrapS if > 0 value for {@link GL#GL_TEXTURE_WRAP_S}
-     * @param wrapT if > 0 value for {@link GL#GL_TEXTURE_WRAP_T}
-     * @return
-     */
-    public boolean init(GL gl, int magFilter, int minFilter, int wrapS, int wrapT) {
-        int textureInternalFormat, textureDataFormat, textureDataType;
-
-        if(gl.isGL2()) { 
-            textureInternalFormat=GL.GL_RGBA8;
-            textureDataFormat=GL2.GL_BGRA;
-            textureDataType=GL2.GL_UNSIGNED_INT_8_8_8_8_REV;
-        } else if(gl.isGLES()) { 
-            textureInternalFormat=GL.GL_RGBA;
-            textureDataFormat=GL.GL_RGBA;
-            textureDataType=GL.GL_UNSIGNED_BYTE;
-        } else {
-            textureInternalFormat=GL.GL_RGB;
-            textureDataFormat=GL.GL_RGB;
-            textureDataType=GL.GL_UNSIGNED_BYTE;
-        }
-        return init(gl, textureInternalFormat, textureDataFormat, textureDataType, magFilter, minFilter, wrapS, wrapT);
-    }
-
     private boolean checkNoError(GL gl, int err, String exceptionMessage) {
         if(GL.GL_NO_ERROR != err) {
             if(null != gl) {
@@ -161,35 +139,36 @@ public class FBObject {
         }
         return true;
     }
-        
+
+    private final void checkInitialized() {
+        if(!initialized) {
+            throw new GLException("FBO not initialized, call init(GL) first.");
+        }                
+    }
+    
+    private final void checkBound(GL gl, boolean shallBeBound) {
+        checkInitialized();
+        if(bound != shallBeBound) {
+            final String s0 = shallBeBound ? "not" : "already" ; 
+            throw new GLException("FBO "+s0+" bound "+toString());
+        }
+        checkNoError(null, gl.glGetError(), "FBObject pre"); // throws GLException if error
+    }
+
     /**
      * Initializes this FBO's instance with it's texture.
      * 
-     * Leaves the FBO bound!
+     * <p>Leaves the FBO bound!</p>
      * 
      * @param gl the current GL context
-     * @param textureInternalFormat internalFormat parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
-     * @param textureDataFormat format parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
-     * @param textureDataType type parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
-     * @param magFilter if > 0 value for {@link GL#GL_TEXTURE_MAG_FILTER}
-     * @param minFilter if > 0 value for {@link GL#GL_TEXTURE_MIN_FILTER} 
-     * @param wrapS if > 0 value for {@link GL#GL_TEXTURE_WRAP_S}
-     * @param wrapT if > 0 value for {@link GL#GL_TEXTURE_WRAP_T}
-     * @return true if successful otherwise false
+     * @throws GLException in case of an error
      */
-    public boolean init(GL gl, int textureInternalFormat, int textureDataFormat, int textureDataType,
-                               int magFilter, int minFilter, int wrapS, int wrapT) {
-        checkBound(false);
-        if(0<fb || 0<fbo_tex) {
-            throw new GLException("FBO already initialized (fb "+fb+", tex "+fbo_tex+")");
-        }
-        
+    public void init(GL gl) throws GLException {
+        if(initialized) {
+            throw new GLException("FBO already initialized");
+        }        
         checkNoError(null, gl.glGetError(), "FBObject Init.pre"); // throws GLException if error
-        
-        texInternalFormat=textureInternalFormat; 
-        texDataFormat=textureDataFormat;
-        texDataType=textureDataType;
-
+                
         // generate fbo ..
         int name[] = new int[1];
 
@@ -206,16 +185,86 @@ public class FBObject {
             checkNoError(gl, GL.GL_INVALID_VALUE, "FBObject Init.isFB"); // throws GLException
         }
         bound = true;        
+        initialized = true;
+        
+        updateStatus(gl);        
+    }
 
-        gl.glGenTextures(1, name, 0);
-        fbo_tex = name[0];
-        if(fbo_tex==0) {
+    /**
+     * Attaches a[nother] Texture2D Color Buffer to this FBO's instance,
+     * selecting the texture data type and format automatically.
+     * <p>This may be done as many times as many color attachments are supported,
+     * see {@link GL2GL3#GL_MAX_COLOR_ATTACHMENTS}.</p> 
+     * 
+     * <p>Assumes a bound FBO</p>
+     * <p>Leaves the FBO bound!</p>
+     * 
+     * @param gl the current GL context
+     * @param texUnit the desired texture unit ranging from [0..{@link GL2#GL_MAX_TEXTURE_UNITS}-1], or -1 if no unit shall be activate at {@link #use(GL, int)}
+     * @param magFilter if > 0 value for {@link GL#GL_TEXTURE_MAG_FILTER}
+     * @param minFilter if > 0 value for {@link GL#GL_TEXTURE_MIN_FILTER} 
+     * @param wrapS if > 0 value for {@link GL#GL_TEXTURE_WRAP_S}
+     * @param wrapT if > 0 value for {@link GL#GL_TEXTURE_WRAP_T}
+     * @return idx of the new attached texture, otherwise -1
+     * @throws GLException in case of an error
+     */
+    public int attachTexture2D(GL gl, int texUnit, int magFilter, int minFilter, int wrapS, int wrapT) throws GLException {
+        final int textureInternalFormat, textureDataFormat, textureDataType;
+        if(gl.isGL2()) { 
+            textureInternalFormat=GL.GL_RGBA8;
+            textureDataFormat=GL2.GL_BGRA;
+            textureDataType=GL2.GL_UNSIGNED_INT_8_8_8_8_REV;
+        } else if(gl.isGLES()) { 
+            textureInternalFormat=GL.GL_RGBA;
+            textureDataFormat=GL.GL_RGBA;
+            textureDataType=GL.GL_UNSIGNED_BYTE;
+        } else {
+            textureInternalFormat=GL.GL_RGB;
+            textureDataFormat=GL.GL_RGB;
+            textureDataType=GL.GL_UNSIGNED_BYTE;
+        }
+        return attachTexture2D(gl, texUnit, textureInternalFormat, textureDataFormat, textureDataType, magFilter, minFilter, wrapS, wrapT);
+    }
+    
+    /**
+     * Attaches a[nother] Texture2D Color Buffer to this FBO's instance,
+     * selecting the texture data type and format automatically.
+     * <p>This may be done as many times as many color attachments are supported,
+     * see {@link GL2GL3#GL_MAX_COLOR_ATTACHMENTS}.</p> 
+     * 
+     * <p>Assumes a bound FBO</p>
+     * <p>Leaves the FBO bound!</p>
+     * 
+     * @param gl the current GL context
+     * @param texUnit the desired texture unit ranging from [0..{@link GL2#GL_MAX_TEXTURE_UNITS}-1], or -1 if no unit shall be activate at {@link #use(GL, int)}
+     * @param textureInternalFormat internalFormat parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
+     * @param textureDataFormat format parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
+     * @param textureDataType type parameter to {@link GL#glTexImage2D(int, int, int, int, int, int, int, int, long)}
+     * @param magFilter if > 0 value for {@link GL#GL_TEXTURE_MAG_FILTER}
+     * @param minFilter if > 0 value for {@link GL#GL_TEXTURE_MIN_FILTER} 
+     * @param wrapS if > 0 value for {@link GL#GL_TEXTURE_WRAP_S}
+     * @param wrapT if > 0 value for {@link GL#GL_TEXTURE_WRAP_T}
+     * @return index of the texture colorbuffer if bound and configured successfully, otherwise -1
+     * @throws GLException in case the texture colorbuffer couldn't be allocated
+     */
+    public int attachTexture2D(GL gl, int texUnit,
+                               int textureInternalFormat, int textureDataFormat, int textureDataType,
+                               int magFilter, int minFilter, int wrapS, int wrapT) throws GLException {
+        checkBound(gl, true);
+        final int fbo_tex_idx = fbo_tex_num;
+        gl.glGenTextures(1, fbo_tex_names, fbo_tex_num);
+        if(fbo_tex_names[fbo_tex_idx]==0) {
             throw new GLException("null generated texture");
         }
-        gl.glBindTexture(GL.GL_TEXTURE_2D, fbo_tex);
+        fbo_tex_units[fbo_tex_idx] = texUnit;
+        fbo_tex_num++;
+        if(0<=texUnit) {
+            gl.glActiveTexture(GL.GL_TEXTURE0 + texUnit);
+        }
+        gl.glBindTexture(GL.GL_TEXTURE_2D, fbo_tex_names[fbo_tex_idx]);
         checkNoError(gl, gl.glGetError(), "FBObject Init.bindTex");  // throws GLException if error        
-        gl.glTexImage2D(GL.GL_TEXTURE_2D, 0, texInternalFormat, width, height, 0,
-                        texDataFormat, texDataType, null);
+        gl.glTexImage2D(GL.GL_TEXTURE_2D, 0, textureInternalFormat, width, height, 0,
+                        textureDataFormat, textureDataType, null);
         checkNoError(gl, gl.glGetError(), "FBObject Init.texImage2D");  // throws GLException if error        
         if( 0 < magFilter ) {
             gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, magFilter);
@@ -232,31 +281,32 @@ public class FBObject {
 
         // Set up the color buffer for use as a renderable texture:
         gl.glFramebufferTexture2D(GL.GL_FRAMEBUFFER,
-                                  GL.GL_COLOR_ATTACHMENT0,
-                                  GL.GL_TEXTURE_2D, fbo_tex, 0); 
+                                  GL.GL_COLOR_ATTACHMENT0 + colorattachment_num++,
+                                  GL.GL_TEXTURE_2D, fbo_tex_names[fbo_tex_idx], 0); 
 
-        updateStatus(gl);        
-        return isStatusValid();                
+        updateStatus(gl);                
+        return isStatusValid() ? fbo_tex_idx : -1;
     }
-
+    
     /**
-     * Assumes a bound FBO
-     * Leaves the FBO bound!
+     * Attaches one Depth Buffer to this FBO's instance.
+     * <p>This may be done only one time.</p>
+     * 
+     * <p>Assumes a bound FBO</p>
+     * <p>Leaves the FBO bound!</p>
+     * @param gl the current GL context
      * @param depthComponentType {@link GL#GL_DEPTH_COMPONENT16}, {@link GL#GL_DEPTH_COMPONENT24} or {@link GL#GL_DEPTH_COMPONENT32}
-     * @return true if successful otherwise false 
+     * @return true if the depth renderbuffer could be bound and configured, otherwise false
+     * @throws GLException in case the depth renderbuffer couldn't be allocated or one is already attached.
      */
-    public boolean attachDepthBuffer(GL gl, int depthComponentType) {
-        if(0>=fb || 0>=fbo_tex) {
-            throw new GLException("FBO not initialized (fb "+fb+", tex "+fbo_tex+")");
-        }
+    public boolean attachDepthBuffer(GL gl, int depthComponentType) throws GLException {
+        checkBound(gl, true);
         if(depth_rb != 0) {
             throw new GLException("FBO depth buffer already attached (rb "+depth_rb+")");
-        }
-        checkBound(true);
+        }        
         int name[] = new int[1];
         gl.glGenRenderbuffers(1, name, 0);
-        depth_rb = name[0];
-        
+        depth_rb = name[0];        
         if(depth_rb==0) {
             throw new GLException("null generated renderbuffer");
         }
@@ -273,26 +323,28 @@ public class FBObject {
         gl.glRenderbufferStorage(GL.GL_RENDERBUFFER, depthComponentType, width, height);
         // Set up the depth buffer attachment:
         gl.glFramebufferRenderbuffer(GL.GL_FRAMEBUFFER,
-                                        GL.GL_DEPTH_ATTACHMENT,
-                                        GL.GL_RENDERBUFFER, depth_rb);
+                                     GL.GL_DEPTH_ATTACHMENT,
+                                     GL.GL_RENDERBUFFER, depth_rb);
         updateStatus(gl);
         return isStatusValid();                
     }
     
     /**
-     * Assumes a bound FBO
-     * Leaves the FBO bound!
+     * Attaches one Stencil Buffer to this FBO's instance.
+     * <p>This may be done only one time.</p>
+     * 
+     * <p>Assumes a bound FBO</p>
+     * <p>Leaves the FBO bound!</p>
+     * @param gl the current GL context
      * @param stencilComponentType {@link GL#GL_STENCIL_INDEX1}, {@link GL#GL_STENCIL_INDEX4} or {@link GL#GL_STENCIL_INDEX8}
-     * @return true if successful otherwise false 
+     * @return true if the stencil renderbuffer could be bound and configured, otherwise false
+     * @throws GLException in case the stencil renderbuffer couldn't be allocated  or one is already attached.
      */
-    public boolean attachStencilBuffer(GL gl, int stencilComponentType) {
-        if(0>=fb || 0>=fbo_tex) {
-            throw new GLException("FBO not initialized (fb "+fb+", tex "+fbo_tex+")");
-        }
+    public boolean attachStencilBuffer(GL gl, int stencilComponentType) throws GLException {
+        checkBound(gl, true);
         if(stencil_rb != 0) {
             throw new GLException("FBO stencil buffer already attached (rb "+stencil_rb+")");
         }
-        checkBound(true);
         int name[] = new int[1];
         gl.glGenRenderbuffers(1, name, 0);
         stencil_rb = name[0];
@@ -302,18 +354,23 @@ public class FBObject {
         // Initialize the stencil buffer:
         gl.glBindRenderbuffer(GL.GL_RENDERBUFFER, stencil_rb);
         if(!gl.glIsRenderbuffer(stencil_rb)) {
-            destroy(gl);
-            System.err.println("not a stencilbuffer: "+ depth_rb);
-            return false;            
+            System.err.println("not a stencilbuffer: "+ stencil_rb);
+            name[0] = stencil_rb;
+            gl.glDeleteRenderbuffers(1, name, 0);
+            stencil_rb=0;
+            return false;
         }
         gl.glRenderbufferStorage(GL.GL_RENDERBUFFER, stencilComponentType, width, height);
         gl.glFramebufferRenderbuffer(GL.GL_FRAMEBUFFER,
-                                        GL.GL_STENCIL_ATTACHMENT,
-                                        GL.GL_RENDERBUFFER, stencil_rb);
+                                     GL.GL_STENCIL_ATTACHMENT,
+                                     GL.GL_RENDERBUFFER, stencil_rb);
         updateStatus(gl);        
         return isStatusValid();                
     }
 
+    /**
+     * @param gl the current GL context
+     */
     public void destroy(GL gl) {
         if(bound) {
             unbind(gl);
@@ -331,46 +388,65 @@ public class FBObject {
             gl.glDeleteRenderbuffers(1, name, 0);
             depth_rb=0;
         }
-        if(0!=fbo_tex) {
-            name[0] = fbo_tex;
-            gl.glDeleteTextures(1, name, 0);
-            fbo_tex = 0;
+        if(null!=fbo_tex_names && fbo_tex_num>0) {
+            gl.glDeleteTextures(1, fbo_tex_names, fbo_tex_num);
+            fbo_tex_names = new int[MAX_FBO_TEXTURES];
+            fbo_tex_units = new int[MAX_FBO_TEXTURES];
+            fbo_tex_num = 0;
         }
+        colorattachment_num = 0;
         if(0!=fb) {
             name[0] = fb;
             gl.glDeleteFramebuffers(1, name, 0);
             fb = 0;
         }
+        initialized = false;
     }
 
-    private final void checkBound(boolean shallBeBound) {
-        if(bound != shallBeBound) {
-            final String s0 = shallBeBound ? "not" : "already" ; 
-            throw new GLException("FBO "+s0+" bound "+toString());
-        }
-    }
-    
+    /** 
+     * Bind this FBO 
+     * <p>In case you have attached more than one color buffer,
+     * you may want to setup {@link GL2GL3#glDrawBuffers(int, int[], int)}.</p>
+     * @param gl the current GL context
+     */
     public void bind(GL gl) {
-        checkBound(false);
-        gl.glBindTexture(GL.GL_TEXTURE_2D, fbo_tex);
+        checkBound(gl, false);
         gl.glBindFramebuffer(GL.GL_FRAMEBUFFER, fb);
         bound = true;
     }
 
+    /** 
+     * Unbind FBO, ie bind 'non' FBO 0 
+     * @param gl the current GL context
+     */
     public void unbind(GL gl) {
-        checkBound(true);
-        gl.glBindTexture(GL.GL_TEXTURE_2D, 0);
+        checkBound(gl, true);
         gl.glBindFramebuffer(GL.GL_FRAMEBUFFER, 0);
         bound = false;
     }
 
-    public void use(GL gl) {
-        checkBound(false);
-        gl.glBindTexture(GL.GL_TEXTURE_2D, fbo_tex); // use it ..
+    /** 
+     * Bind the texture with given index.
+     * 
+     * <p>If a valid texture unit was named via {@link #attachTexture2D(GL, int, int, int, int, int) attachTexture2D(..)},
+     * the unit is activated via {@link GL#glActiveTexture(int) glActiveTexture(GL.GL_TEXTURE0 + unit)}.</p>
+     * @param gl the current GL context
+     * @param texIdx index of the texture to use, prev. attached w/  {@link #attachTexture2D(GL, int, int, int, int, int) attachTexture2D(..)}  
+     */
+    public void use(GL gl, int texIdx) {
+        checkBound(gl, false);
+        if(texIdx >= fbo_tex_num) {
+            throw new GLException("Invalid texId, only "+fbo_tex_num+" textures are attached");
+        }
+        if(0<=fbo_tex_units[texIdx]) {
+            gl.glActiveTexture(GL.GL_TEXTURE0 + fbo_tex_units[texIdx]);
+        }
+        gl.glBindTexture(GL.GL_TEXTURE_2D, fbo_tex_names[texIdx]); // use it ..
     }
 
+    /** Unbind texture, ie bind 'non' texture 0 */    
     public void unuse(GL gl) {
-        checkBound(false);
+        checkBound(gl, false);
         gl.glBindTexture(GL.GL_TEXTURE_2D, 0); // don't use it
     }
     
@@ -378,11 +454,16 @@ public class FBObject {
     public final int getWidth() { return width; }
     public final int getHeight() { return height; }       
     public final int getFBName() { return fb; }
-    public final int getTextureName() { return fbo_tex; }
+    public final int getTextureNumber() { return fbo_tex_num; }
+    public final int getTextureName(int idx) { return fbo_tex_names[idx]; }
+    
+    /** @return the named texture unit ranging from [0..{@link GL2#GL_MAX_TEXTURE_UNITS}-1], or -1 if no unit was desired. */
+    public final int getTextureUnit(int idx) { return fbo_tex_units[idx]; }
+    public final int getColorAttachmentNumber() { return colorattachment_num; }
     public final int getStencilBuffer() { return stencil_rb; }
     public final int getDepthBuffer() { return depth_rb; }
     public final String toString() {
-        return "FBO[name "+fb+", size "+width+"x"+height+", tex "+fbo_tex+", depth "+depth_rb+", stencil "+stencil_rb+"]";
+        return "FBO[name "+fb+", size "+width+"x"+height+", color num "+colorattachment_num+", tex num "+fbo_tex_num+", depth "+depth_rb+", stencil "+stencil_rb+"]";
     }
     
     private void updateStatus(GL gl) {
diff --git a/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.fp b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.fp
new file mode 100644
index 000000000..1738d96d1
--- /dev/null
+++ b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.fp
@@ -0,0 +1,11 @@
+//Copyright 2010 JogAmp Community. All rights reserved.
+
+#version 110
+
+varying vec4    frontColor;
+
+void main (void)
+{
+    gl_FragData[0] = vec4( frontColor.r, 0.0, 0.0, 1.0 ); 
+    gl_FragData[1] = vec4( 0.0, frontColor.g, 0.0, 1.0 );
+}
diff --git a/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.vp b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.vp
new file mode 100644
index 000000000..7f95a650a
--- /dev/null
+++ b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-1.vp
@@ -0,0 +1,16 @@
+// Copyright 2010 JogAmp Community. All rights reserved.
+
+#version 110
+
+uniform mat4    gcu_PMVMatrix[2]; // P, Mv, and Mvi
+attribute vec4  gca_Vertices;
+attribute vec4  gca_Colors;
+
+varying vec4    frontColor;
+
+void main(void)
+{
+  frontColor = gca_Colors;
+  gl_Position = gcu_PMVMatrix[0] * gcu_PMVMatrix[1] * gca_Vertices;
+}
+
diff --git a/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.fp b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.fp
new file mode 100644
index 000000000..deac58ce1
--- /dev/null
+++ b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.fp
@@ -0,0 +1,16 @@
+//Copyright 2010 JogAmp Community. All rights reserved.
+
+#version 110
+
+uniform sampler2D gcs_TexUnit0;
+uniform sampler2D gcs_TexUnit1;
+
+varying vec4    frontColor;
+varying vec2      texCoord;
+
+void main (void)
+{
+  vec2 rg = texture2D(gcs_TexUnit0, texCoord).rg + texture2D(gcs_TexUnit1, texCoord).rg;
+  float b = frontColor.b - length(rg);
+  gl_FragData[0] = vec4( rg, b, 1.0 );
+}
\ No newline at end of file
diff --git a/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.vp b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.vp
new file mode 100644
index 000000000..1b2c02328
--- /dev/null
+++ b/src/test/com/jogamp/opengl/test/junit/jogl/demos/es2/shader/fbo-mrt-2.vp
@@ -0,0 +1,18 @@
+//Copyright 2010 JogAmp Community. All rights reserved.
+
+#version 110
+
+uniform mat4    gcu_PMVMatrix[2]; // P, Mv, and Mvi
+attribute vec4  gca_Vertices;
+attribute vec4  gca_Colors;
+attribute vec2  gca_TexCoords;
+
+varying vec4    frontColor;
+varying vec2    texCoord;
+
+void main(void)
+{
+  frontColor = gca_Colors;
+  texCoord = gca_TexCoords;
+  gl_Position = gcu_PMVMatrix[0] * gcu_PMVMatrix[1] * gca_Vertices;
+}
diff --git a/src/test/com/jogamp/opengl/test/junit/jogl/glsl/TestFBOMRTNEWT01.java b/src/test/com/jogamp/opengl/test/junit/jogl/glsl/TestFBOMRTNEWT01.java
new file mode 100644
index 000000000..6c826c221
--- /dev/null
+++ b/src/test/com/jogamp/opengl/test/junit/jogl/glsl/TestFBOMRTNEWT01.java
@@ -0,0 +1,224 @@
+/**
+ * Copyright 2010 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ *
+ *    2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``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 JogAmp Community 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.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+package com.jogamp.opengl.test.junit.jogl.glsl;
+
+import com.jogamp.opengl.util.FBObject;
+import com.jogamp.opengl.util.GLArrayDataServer;
+import com.jogamp.opengl.util.PMVMatrix;
+import com.jogamp.opengl.util.glsl.ShaderCode;
+import com.jogamp.opengl.util.glsl.ShaderProgram;
+import com.jogamp.opengl.util.glsl.ShaderState;
+import com.jogamp.opengl.test.junit.jogl.demos.es2.RedSquare0;
+import com.jogamp.opengl.test.junit.util.MiscUtils;
+import com.jogamp.opengl.test.junit.util.NEWTGLContext;
+import com.jogamp.opengl.test.junit.util.UITestCase;
+
+import java.io.IOException;
+
+import javax.media.opengl.GL;
+import javax.media.opengl.GL2ES2;
+import javax.media.opengl.GL2GL3;
+import javax.media.opengl.GLDrawable;
+import javax.media.opengl.GLProfile;
+import javax.media.opengl.GLUniformData;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestFBOMRTNEWT01 extends UITestCase {
+    static long durationPerTest = 10; // ms
+
+    @Test
+    public void test01() throws InterruptedException {
+        // preset ..
+        final NEWTGLContext.WindowContext winctx = NEWTGLContext.createWindow(GLProfile.getGL2ES2(), 640, 480, true);
+        final GLDrawable drawable = winctx.context.getGLDrawable();
+        final GL _gl = winctx.context.getGL();
+        Assert.assertTrue(_gl.isGL2GL3());
+        final GL2GL3 gl = _gl.getGL2GL3();
+        System.err.println(winctx.context);
+
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        // test code ..        
+        final ShaderState st = new ShaderState();
+        // st.setVerbose(true);
+        
+        final ShaderCode vp0 = ShaderCode.create(gl, GL2ES2.GL_VERTEX_SHADER, 1, RedSquare0.class,
+                "shader", "shader/bin", "fbo-mrt-1");
+        final ShaderCode fp0 = ShaderCode.create(gl, GL2ES2.GL_FRAGMENT_SHADER, 1, RedSquare0.class,
+                "shader", "shader/bin", "fbo-mrt-1");
+        final ShaderProgram sp0 = new ShaderProgram();
+        sp0.add(gl, vp0, System.err);
+        sp0.add(gl, fp0, System.err);       
+        Assert.assertTrue(0<=sp0.program()); 
+        Assert.assertTrue(!sp0.inUse());
+        Assert.assertTrue(!sp0.linked());
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());        
+        st.attachShaderProgram(gl, sp0);
+        
+        final ShaderCode vp1 = ShaderCode.create(gl, GL2ES2.GL_VERTEX_SHADER, 1, RedSquare0.class,
+                "shader", "shader/bin", "fbo-mrt-2");
+        final ShaderCode fp1 = ShaderCode.create(gl, GL2ES2.GL_FRAGMENT_SHADER, 1, RedSquare0.class,
+                "shader", "shader/bin", "fbo-mrt-2");
+        final ShaderProgram sp1 = new ShaderProgram();
+        sp1.add(gl, vp1, System.err);
+        sp1.add(gl, fp1, System.err);       
+        Assert.assertTrue(0<=sp1.program()); 
+        Assert.assertTrue(!sp1.inUse());
+        Assert.assertTrue(!sp1.linked());
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());        
+        st.attachShaderProgram(gl, sp1);
+        st.useProgram(gl, true);
+                        
+        final PMVMatrix pmvMatrix = new PMVMatrix();
+        final GLUniformData pmvMatrixUniform = new GLUniformData("gcu_PMVMatrix", 4, 4, pmvMatrix.glGetPMvMatrixf());
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        st.ownUniform(pmvMatrixUniform);       
+        st.uniform(gl, pmvMatrixUniform);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        
+        final GLArrayDataServer vertices0 = GLArrayDataServer.createGLSL(st, "gca_Vertices", 3, GL.GL_FLOAT, false, 4, GL.GL_STATIC_DRAW);
+        // st.bindAttribLocation(gl, 0, vertices0);
+        vertices0.putf(0); vertices0.putf(1);  vertices0.putf(0);
+        vertices0.putf(1);  vertices0.putf(1);  vertices0.putf(0);
+        vertices0.putf(0); vertices0.putf(0); vertices0.putf(0);
+        vertices0.putf(1);  vertices0.putf(0); vertices0.putf(0);
+        vertices0.seal(gl, true);
+        st.ownAttribute(vertices0, true);
+        vertices0.enableBuffer(gl, false);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        
+        final GLArrayDataServer colors0 = GLArrayDataServer.createGLSL(st, "gca_Colors", 4, GL.GL_FLOAT, false, 4, GL.GL_STATIC_DRAW);
+        // st.bindAttribLocation(gl, 1, colors0);
+        colors0.putf(1); colors0.putf(0);  colors0.putf(1); colors0.putf(1);
+        colors0.putf(0);  colors0.putf(0);  colors0.putf(1); colors0.putf(1);
+        colors0.putf(0); colors0.putf(0); colors0.putf(0); colors0.putf(1);
+        colors0.putf(0);  colors0.putf(1); colors0.putf(1); colors0.putf(1);
+        colors0.seal(gl, true);
+        st.ownAttribute(colors0, true);
+        colors0.enableBuffer(gl, false);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        
+        final GLUniformData texUnit0 = new GLUniformData("gcs_TexUnit0", 0);
+        st.ownUniform(texUnit0);       
+        st.uniform(gl, texUnit0);
+        final GLUniformData texUnit1 = new GLUniformData("gcs_TexUnit1", 1);
+        st.ownUniform(texUnit1);       
+        st.uniform(gl, texUnit1);
+                
+        final GLArrayDataServer texCoords0 = GLArrayDataServer.createGLSL(st, "gca_TexCoords", 2, GL.GL_FLOAT, false, 4, GL.GL_STATIC_DRAW);
+        // st.bindAttribLocation(gl, 2, texCoords0);
+        texCoords0.putf(0f); texCoords0.putf(1f);
+        texCoords0.putf(1f);  texCoords0.putf(1f);
+        texCoords0.putf(0f); texCoords0.putf(0f);
+        texCoords0.putf(1f);  texCoords0.putf(0f);        
+        texCoords0.seal(gl, true);
+        st.ownAttribute(texCoords0, true);
+        texCoords0.enableBuffer(gl, false);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+
+        // FBO w/ 2 texture2D color buffers
+        final FBObject fbo_mrt = new FBObject(drawable.getWidth(), drawable.getHeight());
+        fbo_mrt.init(gl);
+        Assert.assertTrue( 0 == fbo_mrt.attachTexture2D(gl, texUnit0.intValue(), GL.GL_NEAREST, GL.GL_NEAREST, GL2ES2.GL_CLAMP_TO_EDGE, GL2ES2.GL_CLAMP_TO_EDGE) );
+        Assert.assertTrue( 1 == fbo_mrt.attachTexture2D(gl, texUnit1.intValue(), GL.GL_NEAREST, GL.GL_NEAREST, GL2ES2.GL_CLAMP_TO_EDGE, GL2ES2.GL_CLAMP_TO_EDGE) );
+        Assert.assertTrue( fbo_mrt.attachDepthBuffer(gl, GL.GL_DEPTH_COMPONENT16) );
+        Assert.assertTrue( fbo_mrt.isStatusValid() ) ;
+        fbo_mrt.unbind(gl);
+        
+        // misc GL setup
+        gl.glClearColor(1, 1, 1, 1);
+        gl.glEnable(GL2ES2.GL_DEPTH_TEST);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+
+        // reshape
+        pmvMatrix.glMatrixMode(PMVMatrix.GL_PROJECTION);
+        pmvMatrix.glLoadIdentity();
+        pmvMatrix.glOrthof(0f, 1f, 0f, 1f, -10f, 10f);
+        pmvMatrix.glMatrixMode(PMVMatrix.GL_MODELVIEW);
+        pmvMatrix.glLoadIdentity();
+        st.uniform(gl, pmvMatrixUniform);
+        Assert.assertEquals(GL.GL_NO_ERROR, gl.glGetError());
+        
+        final int[] two_buffers = new int[] { GL.GL_COLOR_ATTACHMENT0, GL.GL_COLOR_ATTACHMENT0+1 };
+        final int[] bck_buffers = new int[] { GL2GL3.GL_BACK_LEFT };
+        
+        for(int i=0; i<durationPerTest; i+=50) {
+            // pass 1 - MRT: Red -> buffer0, Green -> buffer1
+            st.attachShaderProgram(gl, sp0);           
+            vertices0.enableBuffer(gl, true);
+            colors0.enableBuffer(gl, true);
+            
+            fbo_mrt.bind(gl);
+            gl.glDrawBuffers(2, two_buffers, 0);
+            gl.glViewport(0, 0, fbo_mrt.getWidth(), fbo_mrt.getHeight());        
+            
+            gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
+            gl.glDrawArrays(GL.GL_TRIANGLE_STRIP, 0, 4);
+            fbo_mrt.unbind(gl);
+            vertices0.enableBuffer(gl, false);
+            colors0.enableBuffer(gl, false);
+            
+            // pass 2 - mix buffer0, buffer1 and blue
+            // rg = buffer0.rg + buffer1.rg, b = Blue - length(rg);
+            st.attachShaderProgram(gl, sp1);
+            vertices0.enableBuffer(gl, true);
+            colors0.enableBuffer(gl, true);
+            texCoords0.enableBuffer(gl, true);
+            gl.glDrawBuffers(1, bck_buffers, 0);
+            
+            gl.glViewport(0, 0, drawable.getWidth(), drawable.getHeight());
+            fbo_mrt.use(gl, 0);
+            fbo_mrt.use(gl, 1);
+            gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
+            gl.glDrawArrays(GL.GL_TRIANGLE_STRIP, 0, 4);
+            fbo_mrt.unuse(gl);
+            vertices0.enableBuffer(gl, false);
+            colors0.enableBuffer(gl, false);
+            texCoords0.enableBuffer(gl, false);
+            
+            drawable.swapBuffers();
+            Thread.sleep(50);
+        }
+        
+        NEWTGLContext.destroyWindow(winctx);
+    }
+    
+    public static void main(String args[]) throws IOException {
+        System.err.println("main - start");
+        for(int i=0; i<args.length; i++) {
+            if(args[i].equals("-time")) {
+                durationPerTest = MiscUtils.atoi(args[++i], (int)durationPerTest);
+            }
+        }
+        String tstname = TestFBOMRTNEWT01.class.getName();
+        org.junit.runner.JUnitCore.main(tstname);
+        System.err.println("main - end");
+    }    
+}
+