glGenVertexArrays(1, &vao) 处的分段错误；
我的 gdb 回溯给出:
My gdb backtrace gives:
(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
信息量不大.Eclipse 调试器至少让我看到它在下面的第 3 行停止:
Not very informative. Eclipse debugger at least lets me see that it stops on line 3 below:
// Create a vertex array object
GLuint vao;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
这是在 gl 编程中很常见的一个块，我什至用相同的块运行其他代码也没有问题.所以我很困惑.
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.
运行 make 的构建输出:
Build output from running make:
g++ -g -DFREEGLUT_STATIC -DGLEW_STATIC -I../../include example1.cpp ../../Commo/InitShader.o -L/usr/lib/mesa -lGLEW -lglut -lGL -lX11 -lm -o example1
包含问题的程序:
// 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 < 64; i++ ) {
for ( int j = 0; j < 64; j++ ) {
GLubyte c = (((i & 0x8) == 0) ^ ((j & 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, &vao );
glBindVertexArray( vao );
// Create and initialize a buffer object
GLuint buffer;
glGenBuffers( 1, &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] > 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( &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;
}
推荐答案
glewExperimental = GL_TRUE;
glewInit();
应该变魔术
实验驱动
GLEW 从图形中获取有关支持的扩展的信息司机.但是，实验性或预发布的驱动程序可能不会报告通过标准机制的每个可用扩展，其中case GLEW 将报告它不受支持.为了规避这种情况，glewExperimental 全局开关可以通过将其设置为GL_TRUE 在调用 glewInit() 之前，确保所有扩展将公开有效的入口点.
GLEW obtains information on the supported extensions from the graphics driver. Experimental or pre-release drivers, however, might not report every available extension through the standard mechanism, in which case GLEW will report it unsupported. To circumvent this situation, the
glewExperimentalglobal switch can be turned on by setting it toGL_TRUEbefore callingglewInit(), which ensures that all extensions with valid entry points will be exposed.
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