DrawArrays() GL_QUAD_STRIP, alpha value is ignored ???

[blizzard]

Hello

in the past I used the alpha value to set the transparence of a color:

gl2.glEnable(GL.GL_BLEND); // Turn Blending On
// set the color red, green, blue , alpha
gl2.glColor4f( color[1], color[2], color[3], color[0]  );

this worked well

Now I changed my code and use vbo´s and DrawArrays(..) and it look like the alpha value is ignored.
Do I have to set something special when I create the ColorPointer ?
Thanks

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static void vboTestOnlyDrawSeveralQuadStrip(GL2 gl2){             gl2.glEnable(GL.GL_BLEND); // Turn Blending On             //--- turn shade Model Flat On      // eaxh quad is filled with one color defined by the last vertex      gl2.glShadeModel(GL2.GL_FLAT);              for(int i=0; i<vboIndexArray.length/2; i++){           // define which Types of Elements are a allowed          gl2.glEnableClientState( GL2.GL_VERTEX_ARRAY );           gl2.glEnableClientState( GL2.GL_COLOR_ARRAY );                   //--- set the vertex pointer          // bind the buffer, from this moment this specific buffer is used          gl2.glBindBuffer(GL2.GL_ARRAY_BUFFER, vboIndexArray[i]);           // Get the Position of the data in the memory          gl2.glVertexPointer(3, GL2.GL_FLOAT, 0, 0);                     //--- set the color pointer             // bind the buffer, from this moment this specific buffer is used          gl2.glBindBuffer(GL2.GL_ARRAY_BUFFER, vboIndexArray[i+(vboIndexArray.length/2)]);           gl2.glColorPointer(4, GL2.GL_FLOAT, 0, 0);                             // draw the Buffer          gl2.glDrawArrays(GL2.GL_QUAD_STRIP, 0,((intCountOfQuads * 2) + 2));                         // unbind the buffer, by using 0          gl2.glBindBuffer(GL2.GL_ARRAY_BUFFER, 0);                         // Disable vertex arrays          gl2.glDisableClientState( GL2.GL_COLOR_ARRAY );           gl2.glDisableClientState( GL2.GL_VERTEX_ARRAY );              }          }//end: void vboTestOnlyDrawSeveralQuadStrip(

[princec]

I don't see anywhere where you've specified what blending mode to use.

Cas

[blizzard]

Ah thank you that was a good hint ..

I forgot to copy 
gl2.glBlendFunc(GL.GL_SRC_ALPHA,GL.GL_ZERO);  // always drawn new

now it work :-)
thanks

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[theagentd]

That would discard the color already there? Isn't glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) the standard blending function for basic 2D blending? GL_ZERO would discard what is already there... >_<

[R.D.]

Maybe he wants something like the DEPTH_TEST? So pixels with a smalle depth will simply be ignored? (Guess this good be used nicely in a map where you render the closest layer first and so on)

[theagentd]

He seems to just want to do finalColor = color * alpha, so I think his problem is resolved already.