GLFW程序不绘制三角形

GLFW program doesn't draw triangle

本文关键字：三角形 绘制 程序 GLFW      更新时间：2023-10-16

我正在运行一个简单的程序来绘制一个红色三角形。但是，它只显示一个黑色窗口。我怀疑这可能是着色器的问题，因为如果我删除着色器，它会完美地绘制一个白色三角形。

这是我的代码：

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
static unsigned int CompileShader(unsigned int type, const std::string& source){
unsigned int id = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(id, 1, &src, nullptr);
glCompileShader(id);
int res;
glGetShaderiv(id, GL_COMPILE_STATUS, &res);
if(res == GL_FALSE){
    int length;
    glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
    char* message = (char*)alloca(length * sizeof(char));
    glGetShaderInfoLog(id, length, &length, message);
    std::cout << "Failed to compile " << (type == GL_VERTEX_SHADER ? "vertex" : "fragment") << " shader!" << std::endl;
    std::cout << message << std::endl;
    glDeleteShader(id);
    return 0;
}
return id;
}

static unsigned int CreateShader(const std::string& vertexShader, const std::string& fragmentShader){
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(GL_VERTEX_SHADER , vertexShader);
unsigned int fs = CompileShader(GL_FRAGMENT_SHADER , fragmentShader);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}

int main(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
    return -1;
glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 4 );
glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 1 );
glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE );
glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );

/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "I Rock", NULL, NULL);
if (!window)
{
    glfwTerminate();
    return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);

if(glewInit() != GLEW_OK)
    std::cout<< "Error!" << std::endl;

float positions[6] = {
    -0.5f, -0.5f,
     0.0f,  0.5f,
     0.5f, -0.5f
};

unsigned int buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER,  6*sizeof(float), positions, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2*sizeof(float), 0);
#define GLSL(version, shader) "#version " #version "n" #shader
const char* vertexShader = GLSL
(
 410 core,
 layout( location = 0 ) in vec4 position;
 void main()
 {
     gl_Position = position;
 }
 );
const char* fragmentShader = GLSL
(
 410 core,
 out vec4 color;
 void main()
 {
     color = vec4( 1.0, 0.0, 0.0, 1.0 );
 }
 );
unsigned int shader = CreateShader(vertexShader, fragmentShader);
glUseProgram(shader);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
    /* Render here */
    glClear(GL_COLOR_BUFFER_BIT);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    /* Swap front and back buffers */
    glfwSwapBuffers(window);
    /* Poll for and process events */
    glfwPollEvents();
}
glDeleteProgram(shader);
glfwTerminate();
return 0;
}

这些是我的规格：

  • GLFW版本：3.2.1 可可NSGL chdir 菜单栏视网膜动态
  • GLEW_VERSION ： 2.1.0
  • GL_VERSION ： 4.1 ATI-1.60.26
  • GL_VENDOR ： ATI技术公司
  • GL_RENDERER ： AMD Radeon R9 M290 OpenGL 引擎
  • GL_SHADING_LANGUAGE_VERSION ： 4.10

在启用顶点属性、设置顶点属性指针和绘制之前，您需要生成并绑定顶点数组对象 (VAO(：

...
unsigned int buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER,  6*sizeof(float), positions, GL_STATIC_DRAW);
// generate & bind VAO
GLuint vao = 0;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2*sizeof(float), 0);
...

VAO 在核心上下文中不是可选的，就像在兼容性中一样。

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