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Getting weird colors when using textures with OpenGL


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#1 The Magical Pot   Members   -  Reputation: 176

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Posted 01 May 2013 - 06:37 AM

Hello!

 

I'm trying to create a framework that takes care of windows, buttons, checkboxes and things like that, but I'm having some problems. At this point I'm trying to build an in-game window by first rendering the frame that consists of textures and then fill the rest of the window with a colored rectangle. The problem that I'm having is that the colors are off completely and also that the color of a non-textured colored rectangle changes the "hue" (if you will) of the colors of textures. When I render both the frame and the rectangle, the rectangle's colors change the hue of the frame, but when I remove the rectangle from the code, the frame has the colors that I want it to have.

 

OpenGL 2.png

 

The image shows these 2 scenarios:

The window to the left is the scenario where I don't render the colored rectangle inside the window and the frame has the colors that I want it to have.

The window to the right is the scenario where I render the colored rectangle inside the window, but the frame changes its colors after the color of the rectangle (it's hard to see the frame, but it's there)

 

This is the code I use in order to render the colored rectangle:

 

 

/******Window fill******/
 
glLoadIdentity(); //Remove any previous transformations
glDisable( GL_TEXTURE_2D ); //Temporarily disable textures so that the colors won't get messed up
 
glTranslatef( box.x + ThemeTemplate->quadWidth, box.y + ThemeTemplate->quadHeight, 0.f ); //Move to rendering point
 
//Render the window fill
        glBegin( GL_QUADS );
            glColor3ub( 0, 17, 34 ); glVertex2f( 0.f,   0.f );
            glColor3ub( 0, 17, 34 ); glVertex2f( box.w - ( ThemeTemplate->quadWidth * 2 ), 0.f );
            glColor3ub( 0, 17, 34 ); glVertex2f( box.w - ( ThemeTemplate->quadWidth * 2 ), box.h - ( ThemeTemplate->quadHeight * 2 ) );
            glColor3ub( 0, 17, 34 ); glVertex2f( 0.f,  box.h - ( ThemeTemplate->quadHeight * 2 ) );
        glEnd();
 
glEnable( GL_TEXTURE_2D ); //Re-enable textures
 
/******---------------******/
 
I don't really know what the problem is, but I have the feeling that I've forgotten to reset something, because the frame has its normal colors at the first frame when I run the application, but at the next frame it changes its colors.


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#2 __SKYe   Members   -  Reputation: 933

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Posted 01 May 2013 - 11:34 AM

Do you set the color to white when you render the rest of the textures?

If you don't have a

glColor3f(1.0f 1.0f, 1.0f);

 

before you draw the textured quads, then any color you've used for something else will also affect the next draws.

 

Also, since in your example you use the same color for every vertex, you can do this:

//Render the window fill
        glColor3ub( 0, 17, 34 );
        glBegin( GL_QUADS );
            glVertex2f( 0.f,    0.f );
            glVertex2f( box.w - ( ThemeTemplate->quadWidth * 2 ), 0.f );
            glVertex2f( box.w - ( ThemeTemplate->quadWidth * 2 ), box.h - ( ThemeTemplate->quadHeight * 2 ) );
            glVertex2f( 0.f,   box.h - ( ThemeTemplate->quadHeight * 2 ) );
        glEnd();

 

There's no need to repeat the glColor* every vertex.



#3 Rld_   Members   -  Reputation: 1329

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Posted 01 May 2013 - 11:48 AM

Pretty much what __SKYe said, keeping that different color will multiply your texture color with your filler color.

 

If that's not it, you might check your drawing order (draw the frame after you draw the filler), although I don't think that's the case here as the frame is still somewhat there.



#4 The Magical Pot   Members   -  Reputation: 176

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Posted 02 May 2013 - 06:40 AM

I had to change both the drawing order and the color. At first I drew the frame and then the rectangle, but I changed it around so that I'm drawing the rectangle first, then "resetting" the color and at the end I draw the frame. Thank you both! :)






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