OpenGL GLFW + GLAD程序不绘制三角形

Question

我试着用GLFW和Glad画一个三角形。但是屏幕不会显示任何东西(我只能清除屏幕)。

我可以打开一个窗口，并清除屏幕为深蓝色(或任何其他颜色)

但是我不能在屏幕上画三角形，我不知道为什么。

我想也许我的GPU没有默认的着色器。

#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string.h>
#include <vector>
void Log(const char* str) {
std::cout << str << std::endl;
}

void error_callback(int error, const char* description)
{
std::cout << "Error Code ["<< stderr << "] Error: n" << description << std::endl;
}
class Shader {
public:
Shader(const std::string& vertexSrc, const std::string& fragSrc) {
// Create an empty vertex shader handle
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
const GLchar* source = vertexSrc.c_str();
glShaderSource(vertexShader, 1, &source, 0);
glCompileShader(vertexShader);
GLint isCompiled = 0;
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &isCompiled);
if (isCompiled == GL_FALSE)
{
GLint maxLength = 0;
glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &maxLength);
std::vector<GLchar> infoLog(maxLength);
glGetShaderInfoLog(vertexShader, maxLength, &maxLength, &infoLog[0]);
glDeleteShader(vertexShader);
return;
}
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
source = fragSrc.c_str();
glShaderSource(fragmentShader, 1, &source, 0);
glCompileShader(fragmentShader);
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &isCompiled);
if (isCompiled == GL_FALSE)
{
GLint maxLength = 0;
glGetShaderiv(fragmentShader, GL_INFO_LOG_LENGTH, &maxLength);
std::vector<GLchar> infoLog(maxLength);
glGetShaderInfoLog(fragmentShader, maxLength, &maxLength, &infoLog[0]);
glDeleteShader(fragmentShader);
glDeleteShader(vertexShader);
return;
}
m_RendererID = glCreateProgram();
glAttachShader(m_RendererID, vertexShader);
glAttachShader(m_RendererID, fragmentShader);
glLinkProgram(m_RendererID);
// Note the different functions here: glGetProgram* instead of glGetShader*.
GLint isLinked = 0;
glGetProgramiv(m_RendererID, GL_LINK_STATUS, (int*)&isLinked);
if (isLinked == GL_FALSE)
{
GLint maxLength = 0;
glGetProgramiv(m_RendererID, GL_INFO_LOG_LENGTH, &maxLength);
std::vector<GLchar> infoLog(maxLength);
glGetProgramInfoLog(m_RendererID, maxLength, &maxLength, &infoLog[0]);
glDeleteProgram(m_RendererID);
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
return;
}
Log("Shader compiled Successfully at:");
std::cout << m_RendererID << std::endl;
glDetachShader(m_RendererID, vertexShader);
glDetachShader(m_RendererID, fragmentShader);
}
~Shader() {
glDeleteProgram(m_RendererID);
}
void Bind() const {
glUseProgram(m_RendererID);
}
void Unbind() const {
glUseProgram(0);
}
private:
uint32_t m_RendererID = 0;
};
int main() {
Log("Initializing...");
glfwSetErrorCallback(error_callback);
if (!glfwInit())
{
// Initialization failed
Log("Initialization Failed");
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
GLFWwindow* window = glfwCreateWindow(1080, 720, "GLFW_GLAD TEST", NULL, NULL);
if (!window)
{
glfwTerminate();
Log("Window or OpenGL Context Failed");
}
glfwMakeContextCurrent(window);
gladLoadGL();
glfwSwapInterval(1);
int width, height;
glfwGetFramebufferSize(window, &width, &height);
glViewport(0, 0, width, height);
//APP CODE
unsigned int m_VertexArray;
unsigned int m_VertexBuffer;
unsigned int m_IndexBuffer;
float vertices[9] = {
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
0.0f,  0.5f, 0.0f
};
// Vertex Array
glGenVertexArrays(1, &m_VertexArray);
glBindVertexArray(m_VertexArray);
// Vertex Buffer
glGenBuffers(1, &m_VertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, m_VertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glDisableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), nullptr);

// Index Buffer
glGenBuffers(1, &m_IndexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_IndexBuffer);
unsigned int indices[3] = {
0, 1, 2,
};
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
std::string vertexSrc = R"(
#version 330

layout(location = 0) in vec3 a_Pos;
void main()
{
gl_Position = vec4(a_Pos, 1);
}
)";
std::string fragmentSrc = R"(
#version 330

layout(location = 0) out vec4 FragColor;
void main()
{
FragColor = vec4(0.8f, 0.5f, 0.2f, 1.0f);
}
)";
Shader* shader = new Shader(vertexSrc, fragmentSrc);
shader->Bind();

while (!glfwWindowShouldClose(window))
{
glViewport(0, 0, width, height);
glClearColor(0.1f, .1f, .14f, 1);
glClear(GL_COLOR_BUFFER_BIT);
glBindVertexArray(m_VertexArray);
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, nullptr);

glfwSwapBuffers(window);
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
return 0;
}

Answer 1

这绝对是错误的。

glDisableVertexAttribArray(0);

您在这里指的是glEnableVertexAttribArray，因此您正在设置的属性指针实际上是使用。对于禁用的属性数组，所有着色器调用将获得一个常量值。

你的着色器也使用#version 330，实际上需要GLSL 330语法，但是:

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

你只请求GL 2.0上下文，而GL 2.0只要求支持GLSL 1.10。如果这要工作将完全取决于您的驱动程序，您可能会得到一些>= 3.3兼容性配置文件，但你不能指望它。

你应该显式地创建一个3.3上下文，并显式地请求一个核心配置文件。