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I can compile and run the program but it creates only a white windows with nothing in it when it is run. I've made sure that the shader files are in the same directory and still it produces nothing else than a window with a white background.

//
// Perspective view of a color cube using LookAt() and Frustum()
//
// Colors are assigned to each vertex and then the rasterizer interpolates
//   those colors across the triangles.
//
#define _CRT_SECURE_NO_WARNINGS
#include "Angel.h"

typedef Angel::vec4  color4;
typedef Angel::vec4  point4;

const int NumVertices = 36; //(6 faces)(2 triangles/face)(3 vertices/triangle)

point4 points[NumVertices];
color4 colors[NumVertices];

// Vertices of a unit cube centered at origin, sides aligned with axes
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 )
};

// RGBA olors
color4 vertex_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( 1.0, 1.0, 1.0, 1.0 ),  // white
    color4( 0.0, 1.0, 1.0, 1.0 )   // cyan
};

// Viewing transformation parameters

GLfloat radius = 1.0;
GLfloat theta = 0.0;
GLfloat phi = 0.0;

const GLfloat  dr = 5.0 * DegreesToRadians;

GLuint  model_view;  // model-view matrix uniform shader variable location

// Projection transformation parameters

GLfloat  left = -1.0, right = 1.0;
GLfloat  bottom = -1.0, top = 1.0;
GLfloat  zNear = 0.5, zFar = 3.0;

GLuint  projection; // projection matrix uniform shader variable location

//----------------------------------------------------------------------------

// quad generates two triangles for each face and assigns colors
//    to the vertices

int Index = 0;

void
quad( int a, int b, int c, int d )
{
    colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
    colors[Index] = vertex_colors[b]; points[Index] = vertices[b]; Index++;
    colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
    colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
    colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
    colors[Index] = vertex_colors[d]; points[Index] = vertices[d]; Index++;
}

//----------------------------------------------------------------------------

// generate 12 triangles: 36 vertices and 36 colors
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 );
}

//----------------------------------------------------------------------------

// OpenGL initialization
void
init()
{
    colorcube();

    // 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(colors),
          NULL, GL_STATIC_DRAW );
    glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(points), points );
    glBufferSubData( GL_ARRAY_BUFFER, sizeof(points), sizeof(colors), colors );

    // Load shaders and use the resulting shader program
    GLuint program = InitShader( "vshader42.glsl", "fshader42.glsl" );
    glUseProgram( program );

    // set up vertex arrays
    GLuint vPosition = glGetAttribLocation( program, "vPosition" );
    glEnableVertexAttribArray( vPosition );
    glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0,
               BUFFER_OFFSET(0) );

    GLuint vColor = glGetAttribLocation( program, "vColor" ); 
    glEnableVertexAttribArray( vColor );
    glVertexAttribPointer( vColor, 4, GL_FLOAT, GL_FALSE, 0,
               BUFFER_OFFSET(sizeof(points)) );

    model_view = glGetUniformLocation( program, "model_view" );
    projection = glGetUniformLocation( program, "projection" );

    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 );

    point4  eye( radius*sin(theta)*cos(phi),
         radius*sin(theta)*sin(phi),
         radius*cos(theta),
         1.0 );
    point4  at( 0.0, 0.0, 0.0, 1.0 );
    vec4    up( 0.0, 1.0, 0.0, 0.0 );

    mat4  mv = LookAt( eye, at, up );
    glUniformMatrix4fv( model_view, 1, GL_TRUE, mv );

    mat4  p = Frustum( left, right, bottom, top, zNear, zFar );
    glUniformMatrix4fv( projection, 1, GL_TRUE, p );

    glDrawArrays( GL_TRIANGLES, 0, NumVertices );

    glutSwapBuffers();
}

//----------------------------------------------------------------------------

void
keyboard( unsigned char key, int x, int y )
{
    switch( key ) {
    case 033: // Escape Key
    case 'q': case 'Q':
        exit( EXIT_SUCCESS );
        break;

    case 'x': left *= 1.1; right *= 1.1; break;
    case 'X': left *= 0.9; right *= 0.9; break;
    case 'y': bottom *= 1.1; top *= 1.1; break;
    case 'Y': bottom *= 0.9; top *= 0.9; break;
    case 'z': zNear  *= 1.1; zFar *= 1.1; break;
    case 'Z': zNear *= 0.9; zFar *= 0.9; break;
    case 'r': radius *= 2.0; break;
    case 'R': radius *= 0.5; break;
    case 'o': theta += dr; break;
    case 'O': theta -= dr; break;
    case 'p': phi += dr; break;
    case 'P': phi -= dr; break;

    case ' ':  // reset values to their defaults
        left = -1.0;
        right = 1.0;
        bottom = -1.0;
        top = 1.0;
        zNear = 0.5;
        zFar = 3.0;

        radius = 1.0;
        theta  = 0.0;
        phi    = 0.0;
        break;
    }

    glutPostRedisplay();
}

//----------------------------------------------------------------------------

void
reshape( int width, int height )
{
    glViewport( 0, 0, width, height );
}

//----------------------------------------------------------------------------

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 );
    glutReshapeFunc( reshape );

    glutMainLoop();
    return 0;
}
4

2 回答 2

2

一些想法:

将您的替换glewInit();为:

glewExperimental = GL_TRUE;  // Added because of http://openglbook.com/glgenvertexarrays-access-violationsegfault-with-glew/    
GLint GlewInitResult = glewInit();
if (GlewInitResult != GLEW_OK) {
    printf("ERROR: %s\n", glewGetErrorString(GlewInitResult));
}

您还应该使用glGetError(). 在我的博客文章中阅读更多详细信息:http: //blog.nobel-joergensen.com/2013/01/29/debugging-opengl-using-glgeterror/

于 2013-06-24T07:09:16.927 回答
1

一些想法:

  1. 您正在请求支持 OpenGL 3.2 的上下文,但从着色器的文件名中我假设您使用的是 GLSL 4.2?那可能是个问题。

  2. InitShaders 会寻找(编译)错误吗?

  3. 消除一个又一个可能的错误来源。绘制全屏四边形而不是几何图形,禁用着色器等。

于 2013-06-24T05:49:19.950 回答