grayaii wrote:
> In a nutshell, here is what I'm doing (I'm using C# with CsGL):
> // Init my textures:
> CsGL.OpenGL.OpenGLTexture2D m_texture1;
> CsGL.OpenGL.OpenGLTexture2D m_texture2;
> m_texture1 = new OpenGLTexture2D("myImage1.PNG");
> m_texture2 = new OpenGLTexture2D("myImage2.PNG");
Check glTexImage2D function in your OpenGLTexture2D class has
RGBA/RGBA8 and not RGB/RGB8 parameters.
>
> // Draw my textures:
> public void Render()
> {
> GL.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
> GL.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
>
> GL.glEnable(GL.GL_BLEND);
> GL.glDisable(GL.GL_DEPTH_TEST);
> GL.glEnable(GL.GL_ALPHA_TEST);
>
> GL.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
>
> // Some of the different things I've tried:
> //GL.glColor4f(1.0f, 0.0f, 1.0f, 1.0f);
>
> //GL.glAlphaFunc(GL.GL_GREATER, 0.0f);
> //GL.glAlphaFunc(GL.GL_NOTEQUAL, 1.0f);
> //GL.glDisable(GL.GL_ALPHA_TEST);
>
> //GL.glTexEnvf(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE,
> GL.GL_COMBINE_ARB);
> //GL.glTexEnvf(GL.GL_TEXTURE_ENV, GL.GL_COMBINE_RGB_ARB,
> GL.GL_ADD);
GL_COMBINE_ARB is an extension (GL_ARB_texture_env_combine) and it is
rather complicated. But it is very fast. You have to set up sources,
operands and functions (up to 3, i believe) for both - color and alpha
final values. Yor say "add colors" but what are sources and operands?
It looks like, for example
*************************************************************
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_ADD);
glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE3);
glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE2);
glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR);
glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_TEXTURE2);
glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
**************************************************************
lTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
> // Draw texture1:
> m_texture1.Bind()
> GL.glBegin(GL.GL_QUADS);
> ... the ususal glTexCoord2f and glVertex2f code ...
> GL.glEnd();
>
> // Draw texture2:
> m_texture2.Bind()
> GL.glBegin(GL.GL_QUADS);
> ... the ususal glTexCoord2f and glVertex2f code ...
> GL.glEnd();
> }
Without multitexture better use simply
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
> I've tried a bunch of different combinations of glAlphaFunc,
> glTexEnvf, and glColor4f (I left some commented out...), but the
> transparent areas of the png files always show up as black. I would
> expect that when texture2 is drawn, I'd be able to see texture1 under
> it.
>
> I would like to take advantage of png's alpha channel, and NOT use bmp
> files. I feel I'm soooo close to a solution, but after a week of
> banging my head and trying different things I feel I need to post
> here.
> Thanks in advance!
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