Blending + Not Showing Texture

OpenGL Development JOGL Development
#1

Hey peeps, just registered cos it seems to be pretty useful this forum. Anyway to the point.
I am currently having a problem with the fact that when i blend my texture it will blend but will blend with white and not the background.
Here is a sample of the code i am using


    public void RenderShipTexture(){

      gl.glEnable(GL_BLEND);
      gl.glColor4d( 1, 1, 1, 0.5 );
      gl.glBindTexture(GL_TEXTURE_2D, texture[2]);
      gl.glEnable(GL_TEXTURE_2D);

      gl.glBegin(GL_QUADS);
        gl.glTexCoord2d(0, 0);             gl.glVertex3d( backLeftOfShipX, backLeftOfShipY, -1);
        gl.glTexCoord2d(1, 0);             gl.glVertex3d( frontLeftOfShipX, frontLeftOfShipY, -1);
        gl.glTexCoord2d(1, 1);             gl.glVertex3d( frontRightOfShipX, frontRightOfShipY, -1);
        gl.glTexCoord2d(0, 1);             gl.glVertex3d( backRightOfShipX, backRightOfShipY, -1);
      gl.glEnd();
      gl.glDisable(GL_TEXTURE_2D);   
        gl.glDisable(GL_BLEND);
      }

   // draw objects
   public void drawShip() {
     gl.glBegin(GL_QUADS);
       gl.glVertex3d(backLeftOfShipX, backLeftOfShipY, backLeftOfShipZ);
       gl.glVertex3d(frontLeftOfShipX, frontLeftOfShipY, frontLeftOfShipZ);
       gl.glVertex3d(frontRightOfShipX, frontRightOfShipY, frontRightOfShipZ);
       gl.glVertex3d(backRightOfShipX, backRightOfShipY, backRightOfShipZ);
     gl.glEnd();
     RenderShipTexture();

     // call circle as to draw a circle that will go around the alien for collision detection
     centrePlayerX = ((backLeftOfShipX + backRightOfShipX + frontLeftOfShipX + frontRightOfShipX)/4);
     centrePlayerY = ((backLeftOfShipY + backRightOfShipY + frontLeftOfShipY + frontRightOfShipY)/4);
     //centrePlayerZ = ((backLeftOfShipZ + backRightOfShipZ + frontLeftOfShipZ + frontRightOfShipZ)/4);
     gl.glTranslated(centrePlayerX,centrePlayerY,0);
     circle();
     gl.glTranslated(-centrePlayerX,-centrePlayerY,0);
   }

i believe it is something to do with the color as it is set to white, but how can i get this to directly blend with the background and not care about the colours??

Oh and another thing where is it best to blend? a texture or when creating a quad? i thought it would have been the texture itself

Any help is greatly appreciated

Tim

#2

Hi,

First of all, you don’t need to render the Quad first without a texture and then with the texture. The call to RenderShipTexture() should be all, no drawing the vertices before that.
Secondly, you need to specify a Blending-Function for your drawing if you want your texture to blend with the background, right now, you are probably doing no blending at all. Take a look at glBlendFunc(…)
Thirdly, you will have to align your quad that gets textured to the screen. I don’t know, if your vertex-coords are right for this. if not, search for billboarding on google, that should give you some hints as well.

Well, I hope, I was able to help a bit.

Jan