Question

我正在学习来自第6版的opengl，我似乎无法从书中给出的以下代码中画出三角形。

#include <iostream>
#include "externalErrorFix.h"
#include "sb6.h"


GLuint compile_shaders(void)
{
    GLuint vertex_shader;
    GLuint fragment_shader;
    GLuint program;

    //GLSL shader sources 
    static const GLchar *vertex_shader_source[] =
    {
        "#version 430 core                                                  \n"
        "                                                                   \n"
        "void main(void)                                                    \n"
        "{                                                                  \n"
        "   const vec4 vertices[3] = vec4[3](vec4( 0.25, -0.25, 0.5, 1.0),  \n"
        "                                   vec4(-0.25, -0.25, 0.5, 1.0),   \n"
        "                                   vec4(0.25, 0.25, 0.5, 1.0));    \n"
        "                                                                   \n"
        "   gl_postion = vertices[gl_VertexID];                             \n"
        "}                                                                  \n"
    };
    static const GLchar *fragment_shader_source[] =
    {
        "#version 430 core                              \n"
        "                                               \n"
        "out vec4 color;                                \n"
        "void main(void)                                \n"
        "{                                              \n"
        "   color = vec4(0.0, 1.0, 0.0, 1.0);           \n"
        "}                                              \n"
    };

    //create and compile vertex shaders
    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, vertex_shader_source, NULL);
    glCompileShader(vertex_shader);

    //create and compile fragment shader
    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, fragment_shader_source, NULL);
    glCompileShader(fragment_shader);

    //create a program attach shaders and link it 
    program = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);

    glDeleteShader(vertex_shader);
    glDeleteShader(fragment_shader);

    return program;
}


class my_application : public sb6::application
{

private:
    GLuint render_program;
    GLuint vertex_array_object;

public:

    void startup()
    {
        render_program = compile_shaders();
        glGenVertexArrays(1, &vertex_array_object);
        glBindVertexArray(vertex_array_object);
    }
    void shutdown()
    {
        glDeleteVertexArrays(1, &vertex_array_object);
        glDeleteProgram(render_program);
        glDeleteVertexArrays(1, &vertex_array_object);
    }
    void render(double currentTime)
    {
        const GLfloat color[] = { 0.0f,0.2f,0.0f,1.0f };
        glClearBufferfv(GL_COLOR, 0, color);

        glUseProgram(render_program);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        //glPointSize(10.0f);
    }

    /*
    // First program 
    void render(double currentTime)
    {
        const GLfloat color[] = { 
                                    (float)sin(currentTime) * 0.5f + 0.5f,
                                    (float)cos(currentTime) * 0.5f + 0.5f,
                                    0.0f,1.0f 
                                };

        glClearBufferfv(GL_COLOR, 0, color);
    }*/
};
DECLARE_MAIN(my_application);

Answer 1

似乎有一些拼写错误：

gl_postion代替gl_Position
out vec4 color缺少分号out vec4 color;
glDeleteVertexArrays(1, &vertex_array_object);在关闭功能中出现两次

此外，类my_application中缺少init()函数。它应该特别呼叫sb6::application::init()。

如果它仍然无效，那么该书似乎维护了一个包含所有样本here的存储库。也许他们会纠正那里的一切。

OpenGL-三角形没有显示？

1 个答案: