glCreateShader正在崩溃

Question

我应该有Glew和Glut的最新版本,所以不应该是问题.一切都应该链接,我正在使用MS visual studio 2010.我的程序编译但是当我到glCreateShader(GL_FRAGMENT_SHADER)它显示错误:"0xC0000005:访问冲突."

我的节目:

#include <GL\glew.h>
#include <GL\glut.h>
#include <stdio.h>
#include <stdlib.h>

GLuint program;

static char* readShaderSource(const char * shaderFile)
{
    FILE* fp = fopen(shaderFile, "r");
    char* buf;
    long size;

    if (fp == NULL) return NULL; 
    fseek(fp, 0L, SEEK_END);//go to end
    size = ftell(fp);       //get size
    fseek(fp, 0L, SEEK_SET);//go to begining

    buf = (char*) malloc((size +1) * sizeof(char));
    fread(buf, 1, size, fp);
    buf[size] = NULL;
    fclose(fp);
    return buf;
}

static void initShader(const GLchar * fsFile)
{
    GLint status;
    GLchar * fSource;
    GLuint fShader;
    GLuint fShader2;

    //read file
    fSource = readShaderSource(fsFile);
    if (fSource == NULL)
    {
        printf("Fail to load file");
        exit(EXIT_FAILURE);
    }

    //Create program and shader object
    fShader2 = glCreateShader(GL_VERTEX_SHADER);
    fShader = glCreateShader(GL_FRAGMENT_SHADER);
    program = glCreateProgram();

    //Attach shaders to program
    glAttachShader(program, fShader);

    //read shaders
    glShaderSource(fShader, 1, (const GLchar**) &fSource, NULL);

    //compile fragment shader
    glCompileShader(fShader);

    //error check
    glGetShaderiv(fShader, GL_COMPILE_STATUS, &status);
    if (status == GL_FALSE)
    {
        printf("Failed to compile the fragment shader.");
        exit(EXIT_FAILURE);
    }

    //link and error check
    glLinkProgram(program);
    glGetProgramiv(program, GL_LINK_STATUS, &status);
    if (status == GL_FALSE)
    {
        printf("program error");
        exit(EXIT_FAILURE);
    }

    //use program object
    glUseProgram(program);

    //set up uniform parameter
    //skipped for now
}

int main(int argc, char ** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500,500);
    glutCreateWindow("Matrix Fractal");
    glClearColor(1.0, 1.0, 1.0, 1.0);
    gluOrtho2D(0.0,0.0,(GLfloat) 500, (GLfloat) 500);

    glutDisplayFunc(draw);
    glutReshapeFunc(reshape);

    initShader("fsFractal.glsl");

    glutMainLoop();
}

Answer 1

您必须先初始化GLEW才能使用它:

GLenum err = glewInit();

Answer 2

还有另一种情况可能会发生这种情况，但条件并不明显。如果您决定在应用程序中使用 glfw 和 glew，您也可以以 glCreateShader() ACCESS_VIOLATION 结尾，如果您编写：

glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

如果您将此行更改为

glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);

由于 NULL 函数指针 glCreateShader() 导致的 ACCESS_VIOLATION 消失了。

不要问我，glew 和 glfw 这两个库如何相互干扰......巫术警报！