Question

嗨，伙计们，我是opengl世界的新手，所以就像一周我试图了解opengl是如何工作的。所以我放下了我的代码使用不同的例子，我编译它没有问题。但是立方体没有出现，我不知道为什么。任何人都可以向我解释我的错误吗？这里有代码：

#define GL_GLEXT_PROTOTYPES

#include <GL/glew.h>
#include <iostream>
#include <GL/gl.h>
#include <GL/freeglut.h>



using namespace std;

void display(void);

int main(int argc, char ** argv)
{

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA);
    glutInitWindowSize(512, 512);

    glutCreateWindow(argv[0]);


    glutInitContextVersion(4, 5);
    glutInitContextProfile(GLUT_CORE_PROFILE);
    cout<< glGetString(GL_VERSION)<< endl;
    if (glewInit()) {
        cerr << "Unable to initialize GLEW ... exiting" << endl;
        exit(EXIT_FAILURE);
    }   


    GLuint i;
    GLuint vertex[1];

    glGenVertexArrays(3*12,vertex);
    glBindVertexArray(vertex[0]);
    static const GLfloat fl[] = {
    0.583f,  0.771f,  0.014f,
    0.609f,  0.115f,  0.436f,
    0.327f,  0.483f,  0.844f,
    0.822f,  0.569f,  0.201f,
    0.435f,  0.602f,  0.223f,
    0.310f,  0.747f,  0.185f,
    0.597f,  0.770f,  0.761f,
    0.559f,  0.436f,  0.730f,
    0.359f,  0.583f,  0.152f,
    0.483f,  0.596f,  0.789f,
    0.559f,  0.861f,  0.639f,
    0.195f,  0.548f,  0.859f,
    0.014f,  0.184f,  0.576f,
    0.771f,  0.328f,  0.970f,
    0.406f,  0.615f,  0.116f,
    0.676f,  0.977f,  0.133f,
    0.971f,  0.572f,  0.833f,
    0.140f,  0.616f,  0.489f,
    0.997f,  0.513f,  0.064f,
    0.945f,  0.719f,  0.592f,
    0.543f,  0.021f,  0.978f,
    0.279f,  0.317f,  0.505f,
    0.167f,  0.620f,  0.077f,
    0.347f,  0.857f,  0.137f,
    0.055f,  0.953f,  0.042f,
    0.714f,  0.505f,  0.345f,
    0.783f,  0.290f,  0.734f,
    0.722f,  0.645f,  0.174f,
    0.302f,  0.455f,  0.848f,
    0.225f,  0.587f,  0.040f,
    0.517f,  0.713f,  0.338f,
    0.053f,  0.959f,  0.120f,
    0.393f,  0.621f,  0.362f,
    0.673f,  0.211f,  0.457f,
    0.820f,  0.883f,  0.371f,
    0.982f,  0.099f,  0.879f
};

    glGenBuffers(1,&i);
    glBindBuffer(GL_ARRAY_BUFFER,i);
    glBufferData(GL_ARRAY_BUFFER,sizeof(fl),fl,GL_STATIC_DRAW);
    glEnableVertexAttribArray(1);

    const GLchar* vvs="#version 450\n"
    "in vec3 vp;\n"
    "void main() {\n"
    "  gl_Position = vec4(vp, 1.0);\n"
    "}\n";
    const GLchar* gg=
    "#version 450 core"
    "out vec4 fColor;"
    "void"
    "main()"
    "{"
    "fColor = vec4(0.0, 0.0, 1.0, 1.0);"
    "}";

    GLint sh= glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(sh,1,&vvs,NULL);
    glShaderSource(sh,1,&gg,NULL);
    glCompileShader(sh);

    GLint program=glCreateProgram();
    glAttachShader(program,sh);
    glLinkProgram(program);

        glUseProgram(program);
glVertexAttribPointer(
    1,                                // attribute. No particular reason for 1, but must match the layout in the shader.
    3,                                // size
    GL_FLOAT,                         // type
    GL_FALSE,                         // normalized?
    0,                                // stride
    (void*)0                          // array buffer offset
);

    glDisableVertexAttribArray(1);
    glutDisplayFunc(display);
    glutMainLoop();
}


void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);



    glDrawArrays(GL_TRIANGLES,0,12*3);
    glutSwapBuffers();
    glFlush();
}

Answer 1

在Glew init之后添加以下代码：

GLuint VBO;
GLuint VAO;

glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);

static const GLfloat fl[] = {
    0.583f,  0.771f,  0.014f,
    0.609f,  0.115f,  0.436f,
    0.327f,  0.483f,  0.844f,
    0.822f,  0.569f,  0.201f,
    0.435f,  0.602f,  0.223f,
    0.310f,  0.747f,  0.185f,
    0.597f,  0.770f,  0.761f,
    0.559f,  0.436f,  0.730f,
    0.359f,  0.583f,  0.152f,
    0.483f,  0.596f,  0.789f,
    0.559f,  0.861f,  0.639f,
    0.195f,  0.548f,  0.859f,
    0.014f,  0.184f,  0.576f,
    0.771f,  0.328f,  0.970f,
    0.406f,  0.615f,  0.116f,
    0.676f,  0.977f,  0.133f,
    0.971f,  0.572f,  0.833f,
    0.140f,  0.616f,  0.489f,
    0.997f,  0.513f,  0.064f,
    0.945f,  0.719f,  0.592f,
    0.543f,  0.021f,  0.978f,
    0.279f,  0.317f,  0.505f,
    0.167f,  0.620f,  0.077f,
    0.347f,  0.857f,  0.137f,
    0.055f,  0.953f,  0.042f,
    0.714f,  0.505f,  0.345f,
    0.783f,  0.290f,  0.734f,
    0.722f,  0.645f,  0.174f,
    0.302f,  0.455f,  0.848f,
    0.225f,  0.587f,  0.040f,
    0.517f,  0.713f,  0.338f,
    0.053f,  0.959f,  0.120f,
    0.393f,  0.621f,  0.362f,
    0.673f,  0.211f,  0.457f,
    0.820f,  0.883f,  0.371f,
    0.982f,  0.099f,  0.879f
};

glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(fl), fl, GL_STATIC_DRAW);

const GLchar* vertShaderSource = "#version 450 core\n"
    "in vec3 vp;\n"
    "void main() {\n"
    "  gl_Position = vec4(vp, 1.0);\n"
    "}\n";

const GLchar* fragShaderSource =
    "#version 450 core\n"
    "out vec4 fColor;\n"
    "void main()"
    "{"
    "fColor = vec4(0.0, 0.0, 1.0, 1.0);"
    "}";

GLint vertShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertShader, 1, &vertShaderSource, NULL);
glCompileShader(vertShader);

GLint fragShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragShader, 1, &fragShaderSource, NULL);
glCompileShader(fragShader);

GLint program = glCreateProgram();
glAttachShader(program, vertShader);
glAttachShader(program, fragShader);
glLinkProgram(program);

glUseProgram(program);

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);

然后画画。

你到处都遇到问题的代码，你只是复制并粘贴它，不是吗？这是我在为某些x值添加负值之前和之后得到的结果。我不认为它是一个立方体，我认为它是随机点。

Answer 2

从它的外观来看，你用片段字符串覆盖了顶点着色器代码。您需要分别与glCreateShader和GL_VERTEX_SHADER进行两次GL_FRAGMENT_SHADER来电，以及另一个glAttachShader（对同一个节目）。

Answer 3

除了另外两个答案：

您必须在片段着色器代码中添加换行符。你应该检查它们是否已成功编译和链接。
您认为vp属性已分配位置1，但这不保证。您可以向着色器添加布局限定符，也可以查询属性位置。

OpenGl立方体未显示

3 个答案: