opengl 来画个三角形

opengl 来画个三角形

这次我们通过顶点数组的方式来画三角形。

#include "glew.h"
#include <glfw3.h>

int main(void)
{
	GLFWwindow* window;

	/* Initialize the library */
	if (!glfwInit())
		return -1;

	/* Create a windowed mode window and its OpenGL context */
	window = glfwCreateWindow(480, 320, "Hello World", NULL, NULL);
	if (!window)
	{
		glfwTerminate();
		return -1;
	}

	/* Make the window's context current */
	glfwMakeContextCurrent(window);

	// Needed in core profile
	if( glewInit() != GLEW_OK)
	{
		glfwTerminate();
		return -1;
	}

	// An array of 3 vectors which represents 3 vertices
	static const GLfloat g_vertex_buffer_data[] = {
		-1.0f,-1.0f,0.0f,
		1.0f,-1.0f,0.0f,
		0.0f,1.0f,0.0f,
	};

	
	//This will identify our vertex buffer
	GLuint vertexbuffer;

	
	//Generate 1 buffer,put the resulting identifier in vertexbuffer
	glGenBuffers(1,&vertexbuffer);		

	//The following commands will talk about our 'vertexbuffer' buffer
	glBindBuffer(GL_ARRAY_BUFFER,vertexbuffer);

	//Give our vertices to OpenGL.
	glBufferData(GL_ARRAY_BUFFER,sizeof(g_vertex_buffer_data),g_vertex_buffer_data,GL_STATIC_DRAW);

	/* Loop until the user closes the window */
	while (!glfwWindowShouldClose(window))
	{
		
		glEnableVertexAttribArray(0);		
		glVertexAttribPointer(
			0,			// attribute 0. No particular reason for 0, but must match the layout in the shader.
			3,			// size
			GL_FLOAT,	// type
			GL_FALSE,	// normalized?
			0,			// stride
			(void*)0	// array buffer offset
			);

		glDrawArrays(GL_TRIANGLES,0,3);// Starting from vertex 0; 3 vertices total -> 1 triangle
		glDisableVertexAttribArray(0);

		/* Swap front and back buffers */
		glfwSwapBuffers(window);

		/* Poll for and process events */
		glfwPollEvents();
	}

	glfwTerminate();
	return 0;
}

首先工程里添加glew32.lib，cpp里添加#include "glew.h",引入glew库。glewInit()，glew库初始化。

const GLfloat g_vertex_buffer_data[]  顶点数组。glGenBuffers创建buffer,glBindBuffer激活buffer(指定是哪种类型的buffer),glBufferData传入数据，glEnableVertexAttribArray开户顶点数组属性，glVertexAttribPointer设置顶点数组属性，glDrawArrays画数组，glDisableVertexAttribArray关闭顶点数组属性