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PODrawing the alpha channel correctly in OpenGl
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2010-06-23T21:19:15.487
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2011-03-15T23:11:00.380
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2010-06-24T10:44:49.707
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After loading an image, I have the individual bytes for each channel loaded into an array of unsigned characters. It's passed to a function that projects it as a texture onto a quad. Everything seems to work properly other than the alpha channel, which shows up as the background color. I'm using OpenGL to draw the image. Would I benefit by adding a layering mechanism? Also, how can I achieve the transparent effect that I want? Note: This is the code that I have a feeling needs changed: <pre><code>void SetUpView() { // Set color and depth clear value glClearDepth(1.f); glClearColor(1.f, 0.f, 0.f, 0.f); // Enable Z-buffer read and write glEnable(GL_DEPTH_TEST); glEnable(GL_TEXTURE_2D); glDepthMask(GL_TRUE); glEnable (GL_BLEND); glBlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA); // Setup a perspective projection glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(90.f, 1.f, 1.f, 500.f); }; </code></pre> Also, here's the code to render the quad. <pre><code>void DrawTexturedRect(RectBounds *Verts, Image *Texture) { glBindTexture(GL_TEXTURE_2D, GetTextureID(Texture)); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glPixelZoom(1, -1); glBegin(GL_QUADS); glTexCoord2f(0.0, 1.0); glVertex3f(Verts->corners[0].x, Verts->corners[0].y, Verts->corners[0].z); glTexCoord2f(1.0, 1.0); glVertex3f(Verts->corners[1].x, Verts->corners[1].y, Verts->corners[1].z); glTexCoord2f(1.0, 0.0); glVertex3f(Verts->corners[2].x, Verts->corners[2].y, Verts->corners[2].z); glTexCoord2f(0.0, 0.0); glVertex3f(Verts->corners[3].x, Verts->corners[3].y, Verts->corners[3].z); glEnd(); }; </code></pre> The Image class holds an array of unsigned chars, obtained using OpenIL. Relevant code: <pre><code>loaded = ilLoadImage(filename.c_str()); ilConvertImage(IL_RGBA, IL_UNSIGNED_BYTE); unsigned char *bytes = ilGetData(); //NewImage is an instance of an Image. This is returned and passed to the above function. NewImage->data = bytes; </code></pre> <a href="http://img375.imageshack.us/img375/9585/j120192.png" rel="nofollow noreferrer">Problem http://img375.imageshack.us/img375/9585/j120192.png</a> Thanks
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<c++><opengl><alpha>
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Drawing the alpha channel correctly in OpenGl
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