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I'm working on a project where I want to get OpenGL graphics to display in an X11 window. This needs to be done on Ubuntu 12.04 and I am using Mesa's version of OpenGL ES 2.0 and egl. There are a couple of shaders that get compiled and they work fine, but when I get to the one, gdb is showing that the segfault is happening at glCompile() with this fragment shader:

const char PixmapShaderFrag[] =
      "precision mediump float;                            \n"
      "varying vec2 vTexCoord;                             \n"
      "varying vec4 vColor;                                \n"
      "uniform sampler2D sTexture;                         \n"
      "void main()                                         \n"
      "{                                                   \n"
      "    gl_FragColor = texture2D(sTexture, vTexCoord);  \n"
      "}                                                   \n";

EDIT:

Here is another fragment shader that compiles before the one above and doesn't seem to cause any issues:

const char RectShaderFrag[] =
      "precision mediump float;      \n"
      "varying vec4 vColor;          \n"
      "void main()                   \n"
      "{                             \n"
      "    gl_FragColor = vColor;    \n"
      "}                             \n";

The only big difference between the PixmapShaderFrag shader and the others is texture2D(), so I think that might be what is causing the segfault. Does anyone know if there is a problem with Mesa and using texture2D(), or is there something else wrong with the shader? Is there perhaps another way I can do what texture2D() does even if it requires more shader code?`

Alex
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  • Can you show another shader that actually does work? Mesa is capable of compiling ES and desktop shaders. When an ES shader is compiled with no `#version` directive it is assumed to be ***100 es***; a desktop shader with no `#version` directive assumes ***110***. If for some reason Mesa thinks this is a desktop GLSL shader it might choke on `precision`, since that is not valid in GLSL 110. `#version 100` may change things, though I doubt it. – Andon M. Coleman Jan 18 '14 at 15:52
  • Thanks for the help. I added the code for a shader that does compile into the question. I also tried adding `#version 100` at the beginning of all my shaders, and it still segfaults on compile. – Alex Jan 20 '14 at 18:03

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