title: Color picking in the openGL
body: <p>i've been trying to implement color picking and it just aint working right. the problem is that if initially paint my model in the different colors that are used for the picking (i mean, i give each triangle different color, which is his id color), it works fine (without texture or anything .. ), but if i put texture of the model, and that when the mouse is clicked i paint the model by giving each triangle a different color, it doesnt work..
  here is the code:</p>
  
  <pre><code>public int selection(int x, int y) {        
      GL11.glDisable(GL11.GL_LIGHTING);
      GL11.glDisable(GL11.GL_TEXTURE_2D);
  
      IntBuffer viewport = BufferUtils.createIntBuffer(16); 
      ByteBuffer pixelbuff = BufferUtils.createByteBuffer(16);
  
      GL11.glGetInteger(GL11.GL_VIEWPORT, viewport);              
  
      this.render(this.mesh);
  
      GL11.glReadPixels(x, y, 1, 1, GL11.GL_RGB, GL11.GL_UNSIGNED_BYTE, pixelbuff);
  
      for (int m = 0; m &lt; 3; m++)
          System.out.println(pixelbuff.get(m));
  
     GL11.glEnable(GL11.GL_TEXTURE_2D);
     GL11.glEnable(GL11.GL_LIGHTING);
  
      return 0;
  }
  
  
  public void render(GL_Mesh m, boolean inPickingMode)
  {
      GLMaterial[] materials = m.materials;   // loaded from the .mtl file
      GLMaterial mtl;
      GL_Triangle t;
      int currMtl = -1;
      int i = 0;
  
      // draw all triangles in object
      for (i=0; i &lt; m.triangles.length; ) {
          t = m.triangles[i];
  
          // activate new material and texture
          currMtl = t.materialID;
          mtl = (materials != null &amp;&amp; materials.length&gt;0 &amp;&amp; currMtl &gt;= 0)? materials[currMtl] : defaultMtl;
          mtl.apply();
          GL11.glBindTexture(GL11.GL_TEXTURE_2D, mtl.textureHandle);
  
          // draw triangles until material changes
          for ( ; i &lt; m.triangles.length &amp;&amp; (t=m.triangles[i])!=null &amp;&amp; currMtl == t.materialID; i++) {
                  drawTriangle(t, i, inPickingMode);
  
          }
      }
  }
  </code></pre>
  
  <p>private void drawTriangle(GL_Triangle t, int i, boolean inPickingMode) {</p>
  
  <pre><code>    if (inPickingMode) {
          byte[] triColor = this.triangleToColor(i);
  
          GL11.glColor3ub((byte)triColor[2], (byte)triColor[1], (byte)triColor[0]);
      }
  
      GL11.glBegin(GL11.GL_TRIANGLES);
  
      GL11.glTexCoord2f(t.uvw1.x, t.uvw1.y);
      GL11.glNormal3f(t.norm1.x, t.norm1.y, t.norm1.z);
      GL11.glVertex3f( (float)t.p1.pos.x, (float)t.p1.pos.y, (float)t.p1.pos.z);
  
      GL11.glTexCoord2f(t.uvw2.x, t.uvw2.y);
      GL11.glNormal3f(t.norm2.x, t.norm2.y, t.norm2.z);
      GL11.glVertex3f( (float)t.p2.pos.x, (float)t.p2.pos.y, (float)t.p2.pos.z);
  
      GL11.glTexCoord2f(t.uvw3.x, t.uvw3.y);
      GL11.glNormal3f(t.norm3.x, t.norm3.y, t.norm3.z);
      GL11.glVertex3f( (float)t.p3.pos.x, (float)t.p3.pos.y, (float)t.p3.pos.z);
  
      GL11.glEnd();
  }
  </code></pre>
  
  <p>as you can see, i have a selection function that's called everytime the mouse is clicked, i then disable the lightining and the texture, and then i render the scene again in the unique colors, and then read the pixles buffer, and the call of:
  GL11.glReadPixels(x, y, 1, 1, GL11.GL_RGB, GL11.GL_UNSIGNED_BYTE, pixelbuff);
  <strong>gives me wrong values</strong> .. and its driving me nutz !
  btw, the main render function is render(mesh m, boolean inPickingMode) as u can see, you can also see that there is texture on the model before the mouse clicking ..</p>