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POProblems with GL_LUMINANCE and ATI
 

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  1. POProblems with GL_LUMINANCE and ATI
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    <p>I'm trying to use luminance textures on my ATI graphics card. </p> <p><em>The problem</em>: I'm not being able to correctly retrieve data from my GPU. Whenever I try to read it (using glReadPixels), all it gives me is an 'all-ones' array (1.0, 1.0, 1.0...).</p> <p>You can test it with this code:</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;GL/glew.h&gt; #include &lt;GL/glut.h&gt; static int arraySize = 64; static int textureSize = 8; //static GLenum textureTarget = GL_TEXTURE_2D; //static GLenum textureFormat = GL_RGBA; //static GLenum textureInternalFormat = GL_RGBA_FLOAT32_ATI; static GLenum textureTarget = GL_TEXTURE_RECTANGLE_ARB; static GLenum textureFormat = GL_LUMINANCE; static GLenum textureInternalFormat = GL_LUMINANCE_FLOAT32_ATI; int main(int argc, char** argv) { // create test data and fill arbitrarily float* data = new float[arraySize]; float* result = new float[arraySize]; for (int i = 0; i &lt; arraySize; i++) { data[i] = i + 1.0; } // set up glut to get valid GL context and // get extension entry points glutInit (&amp;argc, argv); glutCreateWindow("TEST1"); glewInit(); // viewport transform for 1:1 pixel=texel=data mapping glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, textureSize, 0.0, textureSize); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glViewport(0, 0, textureSize, textureSize); // create FBO and bind it (that is, use offscreen render target) GLuint fboId; glGenFramebuffersEXT(1, &amp;fboId); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboId); // create texture GLuint textureId; glGenTextures (1, &amp;textureId); glBindTexture(textureTarget, textureId); // set texture parameters glTexParameteri(textureTarget, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(textureTarget, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(textureTarget, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(textureTarget, GL_TEXTURE_WRAP_T, GL_CLAMP); // define texture with floating point format glTexImage2D(textureTarget, 0, textureInternalFormat, textureSize, textureSize, 0, textureFormat, GL_FLOAT, 0); // attach texture glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, textureTarget, textureId, 0); // transfer data to texture //glDrawBuffer(GL_COLOR_ATTACHMENT0_EXT); //glRasterPos2i(0, 0); //glDrawPixels(textureSize, textureSize, textureFormat, GL_FLOAT, data); glBindTexture(textureTarget, textureId); glTexSubImage2D(textureTarget, 0, 0, 0, textureSize, textureSize, textureFormat, GL_FLOAT, data); // and read back glReadBuffer(GL_COLOR_ATTACHMENT0_EXT); glReadPixels(0, 0, textureSize, textureSize, textureFormat, GL_FLOAT, result); // print out results printf("**********************\n"); printf("Data before roundtrip:\n"); printf("**********************\n"); for (int i = 0; i &lt; arraySize; i++) { printf("%f, ", data[i]); } printf("\n\n\n"); printf("**********************\n"); printf("Data after roundtrip:\n"); printf("**********************\n"); for (int i = 0; i &lt; arraySize; i++) { printf("%f, ", result[i]); } printf("\n"); // clean up delete[] data; delete[] result; glDeleteFramebuffersEXT (1, &amp;fboId); glDeleteTextures (1, &amp;textureId); system("pause"); return 0; } </code></pre> <p>I also read somewhere on the internet that ATI cards don't support luminance yet. Does anyone know if this is true?</p>
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    1. USPedro Boechat
    1. USPedro Boechat
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
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      1. POProblems with GL_LUMINANCE and ATI
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      1. VTUpMod
    2. VO
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      1. POProblems with GL_LUMINANCE and ATI
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      1. VTDownMod
    3. VO
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      1. POProblems with GL_LUMINANCE and ATI
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    1. COYou need to provide some actual code. Preferably the code you're actually running. A link to the index for a giant set of tutorials is not helpful. At least link to the one you are trying to use.
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      1. POProblems with GL_LUMINANCE and ATI
      1. USNicol Bolas
    2. COI edited the post and added the code. Thanks, Nicol!
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      1. POProblems with GL_LUMINANCE and ATI
      1. USPedro Boechat
 

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