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