OpenGL笔记五之VBO与VAO

OpenGL笔记五之VBO与VAO

总结自bilibili赵新政老师的教程

code review!

1.VBO

代码

void prepareVBO() {
	//1 创建一个vbo  *******还没有真正分配显存*********
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));

	//2 销毁一个vbo
	GL_CALL(glDeleteBuffers(1, &vbo));

	//3 创建n个vbo
	GLuint vboArr[] = {0, 0, 0};
	GL_CALL(glGenBuffers(3, vboArr));

	//4 销毁n个vbo
	GL_CALL(glDeleteBuffers(3, vboArr));
}

void prepare() {
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};

	//1 生成一个vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));

	//2 绑定当前vbo，到opengl状态机的当前vbo插槽上
	//GL_ARRAY_BUFFER:表示当前vbo这个插槽
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));

	//3 向当前vbo传输数据，也是在开辟显存
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));
}

void prepareSingleBuffer() {
	//1 准备顶点位置数据与颜色数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};

	//2 为位置&颜色数据各自生成一个vbo
	GLuint posVbo = 0, colorVbo = 0;
	GL_CALL(glGenBuffers(1, &posVbo));
	GL_CALL(glGenBuffers(1, &colorVbo));

	//3 给两个分开的vbo各自填充数据
	//position填充数据
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, posVbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW));

	//color填充数据
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, colorVbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW));
}

void prepareInterleavedBuffer() {
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f, 0.0f, 0.0f, 1.0f
	};

	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));

	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));

	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

}
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2.VAO

代码

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GLuint vao = 0;
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}
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3.VBO与VAO对比