[Modern OpenGL系列(三)]用OpenGL绘制一个三角形

时间:2022-12-11 13:29:13

本文已同步发表在CSDN:http://blog.csdn.net/wenxin2011/article/details/51347008


上一篇文章中已经介绍了OpenGL窗口的创建。本文接着说如何用OpenGL绘制一个三角形。

1 . 添加头文件mesh.h,代码如下:

#pragma once

#include <glm\glm.hpp>
#include <GL\glew.h> class Vertex
{
public:
Vertex(const glm::vec3& pos)
{
this->pos = pos;
}
protected:
private:
glm::vec3 pos;
}; class Mesh
{
public:
Mesh(Vertex* vertices, unsigned int numVertices); void Draw(); virtual ~Mesh(); protected:
private:
Mesh(const Mesh& other);
void operator=(const Mesh& other); enum
{
POSITION_VB,
NUM_BUFFERS
}; GLuint m_vertexArrayObject;
GLuint m_vertexArrayBuffers[NUM_BUFFERS];
unsigned int m_drawCount;
};

2 . 添加类mesh.cpp,代码如下:

#include "mesh.h"

Mesh::Mesh(Vertex* vertices, unsigned int numVertices)
{
m_drawCount = numVertices; glGenVertexArrays(1, &m_vertexArrayObject);
glBindVertexArray(m_vertexArrayObject); glGenBuffers(NUM_BUFFERS, m_vertexArrayBuffers);
glBindBuffer(GL_ARRAY_BUFFER, m_vertexArrayBuffers[POSITION_VB]);
glBufferData(GL_ARRAY_BUFFER, numVertices * sizeof(vertices[0]), vertices, GL_STATIC_DRAW); glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0); glBindVertexArray(0);
} Mesh::~Mesh()
{
glDeleteVertexArrays(1, &m_vertexArrayObject);
} void Mesh::Draw()
{
glBindVertexArray(m_vertexArrayObject);
glDrawArrays(GL_TRIANGLES, 0, m_drawCount); glBindVertexArray(0);
}

3 . 修改主类main.cpp,代码如下:

#include <GL\glew.h>
#include "display.h"
#include "mesh.h" int main(int argc, char** argv)
{
// 设置窗体大小和标题
Display display(400, 300, "hello world!"); // 设置三角形顶点
Vertex vertices[] = { Vertex(glm::vec3(-0.5, -0.5, 0)), Vertex(glm::vec3(0, 0.5, 0)), Vertex(glm::vec3(0.5, -0.5, 0)), }; // 生成网格
Mesh mesh(vertices, sizeof(vertices) / sizeof(vertices[0])); while (!display.IsClosed())
{
display.Clear(0.0f, 1.0f, 0.0f, 1.0f); // 绘制三角形
mesh.Draw(); display.Update();// 刷新
} return 0;
}

本文整理自YouTube视频教程#3.5 Intro to Modern OpenGL Tutorial: Meshes


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