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POSegmentation fault at glGenVertexArrays( 1, &vao );
 

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  1. POSegmentation fault at glGenVertexArrays( 1, &vao );
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    <p>My gdb backtrace gives:</p> <pre><code>(gdb) backtrace #0 0x00000000 in ?? () #1 0x0804a211 in init () at example1.cpp:147 #2 0x0804a6bc in main (argc=1, argv=0xbffff3d4) at example1.cpp:283 </code></pre> <p>Not very informative. Eclipse debugger at least lets me see that it stops on line 3 below:</p> <pre><code>// Create a vertex array object GLuint vao; glGenVertexArrays( 1, &amp;vao ); glBindVertexArray( vao ); </code></pre> <p>This is a very common block to see in gl programming, and I'm even running other code with the same block with no problem. So I'm baffled.</p> <p>Build output from running make:</p> <pre><code>g++ -g -DFREEGLUT_STATIC -DGLEW_STATIC -I../../include example1.cpp ../../Commo/InitShader.o -L/usr/lib/mesa -lGLEW -lglut -lGL -lX11 -lm -o example1 </code></pre> <p>Program containing the problem:</p> <pre><code>// rotating cube with two texture objects // change textures with 1 and 2 keys #include "Angel.h" const int NumTriangles = 12; // (6 faces)(2 triangles/face) const int NumVertices = 3 * NumTriangles; const int TextureSize = 64; typedef Angel::vec4 point4; typedef Angel::vec4 color4; // Texture objects and storage for texture image GLuint textures[2]; GLubyte image[TextureSize][TextureSize][3]; GLubyte image2[TextureSize][TextureSize][3]; // Vertex data arrays point4 points[NumVertices]; color4 quad_colors[NumVertices]; vec2 tex_coords[NumVertices]; // Array of rotation angles (in degrees) for each coordinate axis enum { Xaxis = 0, Yaxis = 1, Zaxis = 2, NumAxes = 3 }; int Axis = Xaxis; GLfloat Theta[NumAxes] = { 0.0, 0.0, 0.0 }; GLuint theta; //---------------------------------------------------------------------------- int Index = 0; void quad( int a, int b, int c, int d ) { point4 vertices[8] = { point4( -0.5, -0.5, 0.5, 1.0 ), point4( -0.5, 0.5, 0.5, 1.0 ), point4( 0.5, 0.5, 0.5, 1.0 ), point4( 0.5, -0.5, 0.5, 1.0 ), point4( -0.5, -0.5, -0.5, 1.0 ), point4( -0.5, 0.5, -0.5, 1.0 ), point4( 0.5, 0.5, -0.5, 1.0 ), point4( 0.5, -0.5, -0.5, 1.0 ) }; color4 colors[8] = { color4( 0.0, 0.0, 0.0, 1.0 ), // black color4( 1.0, 0.0, 0.0, 1.0 ), // red color4( 1.0, 1.0, 0.0, 1.0 ), // yellow color4( 0.0, 1.0, 0.0, 1.0 ), // green color4( 0.0, 0.0, 1.0, 1.0 ), // blue color4( 1.0, 0.0, 1.0, 1.0 ), // magenta color4( 0.0, 1.0, 1.0, 1.0 ), // white color4( 1.0, 1.0, 1.0, 1.0 ) // cyan }; quad_colors[Index] = colors[a]; points[Index] = vertices[a]; tex_coords[Index] = vec2( 0.0, 0.0 ); Index++; quad_colors[Index] = colors[a]; points[Index] = vertices[b]; tex_coords[Index] = vec2( 0.0, 1.0 ); Index++; quad_colors[Index] = colors[a]; points[Index] = vertices[c]; tex_coords[Index] = vec2( 1.0, 1.0 ); Index++; quad_colors[Index] = colors[a]; points[Index] = vertices[a]; tex_coords[Index] = vec2( 0.0, 0.0 ); Index++; quad_colors[Index] = colors[a]; points[Index] = vertices[c]; tex_coords[Index] = vec2( 1.0, 1.0 ); Index++; quad_colors[Index] = colors[a]; points[Index] = vertices[d]; tex_coords[Index] = vec2( 1.0, 0.0 ); Index++; } //---------------------------------------------------------------------------- void colorcube() { quad( 1, 0, 3, 2 ); quad( 2, 3, 7, 6 ); quad( 3, 0, 4, 7 ); quad( 6, 5, 1, 2 ); quad( 4, 5, 6, 7 ); quad( 5, 4, 0, 1 ); } //---------------------------------------------------------------------------- void init() { colorcube(); // Create a checkerboard pattern for ( int i = 0; i &lt; 64; i++ ) { for ( int j = 0; j &lt; 64; j++ ) { GLubyte c = (((i &amp; 0x8) == 0) ^ ((j &amp; 0x8) == 0)) * 255; image[i][j][0] = c; image[i][j][1] = c; image[i][j][2] = c; image2[i][j][0] = c; image2[i][j][1] = 0; image2[i][j][2] = c; } } // Initialize texture objects glGenTextures( 2, textures ); glBindTexture( GL_TEXTURE_2D, textures[0] ); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, TextureSize, TextureSize, 0, GL_RGB, GL_UNSIGNED_BYTE, image ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); glBindTexture( GL_TEXTURE_2D, textures[1] ); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, TextureSize, TextureSize, 0, GL_RGB, GL_UNSIGNED_BYTE, image2 ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); glActiveTexture( GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D, textures[0] ); // Create a vertex array object GLuint vao; glGenVertexArrays( 1, &amp;vao ); glBindVertexArray( vao ); // Create and initialize a buffer object GLuint buffer; glGenBuffers( 1, &amp;buffer ); glBindBuffer( GL_ARRAY_BUFFER, buffer ); glBufferData( GL_ARRAY_BUFFER, sizeof(points) + sizeof(quad_colors) + sizeof(tex_coords), NULL, GL_STATIC_DRAW ); // Specify an offset to keep track of where we're placing data in our // vertex array buffer. We'll use the same technique when we // associate the offsets with vertex attribute pointers. GLintptr offset = 0; glBufferSubData( GL_ARRAY_BUFFER, offset, sizeof(points), points ); offset += sizeof(points); glBufferSubData( GL_ARRAY_BUFFER, offset, sizeof(quad_colors), quad_colors ); offset += sizeof(quad_colors); glBufferSubData( GL_ARRAY_BUFFER, offset, sizeof(tex_coords), tex_coords ); // Load shaders and use the resulting shader program GLuint program = InitShader( "vshader71.glsl", "fshader71.glsl" ); glUseProgram( program ); // set up vertex arrays offset = 0; GLuint vPosition = glGetAttribLocation( program, "vPosition" ); glEnableVertexAttribArray( vPosition ); glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(offset) ); offset += sizeof(points); GLuint vColor = glGetAttribLocation( program, "vColor" ); glEnableVertexAttribArray( vColor ); glVertexAttribPointer( vColor, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(offset) ); offset += sizeof(quad_colors); GLuint vTexCoord = glGetAttribLocation( program, "vTexCoord" ); glEnableVertexAttribArray( vTexCoord ); glVertexAttribPointer( vTexCoord, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(offset) ); // Set the value of the fragment shader texture sampler variable // ("texture") to the the appropriate texture unit. In this case, // zero, for GL_TEXTURE0 which was previously set by calling // glActiveTexture(). glUniform1i( glGetUniformLocation(program, "texture"), 0 ); theta = glGetUniformLocation( program, "theta" ); glEnable( GL_DEPTH_TEST ); glClearColor( 1.0, 1.0, 1.0, 1.0 ); } void display( void ) { glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); glUniform3fv( theta, 1, Theta ); glDrawArrays( GL_TRIANGLES, 0, NumVertices ); glutSwapBuffers(); } //---------------------------------------------------------------------------- void mouse( int button, int state, int x, int y ) { if ( state == GLUT_DOWN ) { switch( button ) { case GLUT_LEFT_BUTTON: Axis = Xaxis; break; case GLUT_MIDDLE_BUTTON: Axis = Yaxis; break; case GLUT_RIGHT_BUTTON: Axis = Zaxis; break; } } } //---------------------------------------------------------------------------- void idle( void ) { Theta[Axis] += 0.01; if ( Theta[Axis] &gt; 360.0 ) { Theta[Axis] -= 360.0; } glutPostRedisplay(); } //---------------------------------------------------------------------------- void keyboard( unsigned char key, int mousex, int mousey ) { switch( key ) { case 033: // Escape Key case 'q': case 'Q': exit( EXIT_SUCCESS ); break; case '1': glBindTexture( GL_TEXTURE_2D, textures[0] ); break; case '2': glBindTexture( GL_TEXTURE_2D, textures[1] ); break; } glutPostRedisplay(); } //---------------------------------------------------------------------------- int main( int argc, char **argv ) { glutInit( &amp;argc, argv ); glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH ); glutInitWindowSize( 512, 512 ); glutInitContextVersion( 3, 2 ); glutInitContextProfile( GLUT_CORE_PROFILE ); glutCreateWindow( "Color Cube" ); glewInit(); init(); glutDisplayFunc( display ); glutKeyboardFunc( keyboard ); glutMouseFunc( mouse ); glutIdleFunc( idle ); glutMainLoop(); return 0; } </code></pre>
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    1. USgenpfault
    1. USRooster
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      1. POSegmentation fault at glGenVertexArrays( 1, &vao );
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      1. VTDownMod
    2. VO
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      1. POSegmentation fault at glGenVertexArrays( 1, &vao );
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    3. VO
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      1. This table or related slice is empty.
      1. VTUpMod
    1. CODoes the third line happen to be line 147 of example1.cpp?
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      1. POSegmentation fault at glGenVertexArrays( 1, &vao );
      1. USMarcelo Cantos
    2. COSorry; this isn't enough information to even begin working on this problem. How do you [load your OpenGL function pointers](http://www.opengl.org/wiki/Load_OpenGL_Functions)? Do you use a [library](http://www.opengl.org/wiki/OpenGL_Loading_Library) or do you do it manually? If it's a library, did you initialize it? What library is it? If you do it manually, what pointer value did you get back for `glGenVertexArrays`?
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      1. POSegmentation fault at glGenVertexArrays( 1, &vao );
      1. USNicol Bolas
    3. CO@Marcelo Line 147 is init(), in which that block resides. There's more in init() besides that.
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      1. POSegmentation fault at glGenVertexArrays( 1, &vao );
      1. USRooster
 

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