OpenGL随笔四 opengl通过uniform实现图形颜色动态变化

#define GLEW_STATIC ///////////////////////////////////3
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include
//VBO绘制两个共边的三角形需要六个点
float vertices[] = {
//第一个三角形
-0.5f, -0.5f, 0.0f, //0
0.5f, -0.5f, 0.0f, //1
0.0f, 0.5f, 0.0f, //2
//第二个三角形
//0.5f, -0.5f, 0.0f,
//0.0f, 0.5f, 0.0f,
0.8f, 0.8f, 0.0f, //3
};
//EBO绘制两个共边的三角形只需要四个点
unsigned int indices[] = {
0,1,3,
1,2,3
};

const char* vertexShaderSource =
“#version 330 core \n”
“layout(location=15) in vec3 aPos; \n”
“out vec4 vertexColor; \n”
“void main(){ \n”
“gl_Position = vec4(aPos.x,aPos.y,aPos.z,1.0);}\n”;
const char* fragmentShaderSource =
“#version 330 core \n”
“in vec4 vertexColor; \n”
“uniform vec4 ourColor; \n”
“out vec4 FragColor; \n”
“void main() \n”
“{ \n”
" FragColor = ourColor; \n"
“} \n”;
//输入控制函数声明
void processInput(GLFWwindow* window);
int main() {
//初始化
glfwInit();
//设置版本3.3
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
//设置配置
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//创建窗口
GLFWwindow* window = glfwCreateWindow(800, 600, “OpenGL uniform动态色彩”, NULL, NULL);
if (window == NULL)
{
std::cout << “Failed to create GLFW window” << std::endl;
glfwTerminate();
return -1;
}
//绑定窗口到当前线程
glfwMakeContextCurrent(window);
if (glewInit() != GLEW_OK)
{
std::cout << “Failed to initialize GLEW” << std::endl;
glfwTerminate();
return -1;
}
//设置绘图区域
glViewport(0, 0, 800, 600);
//设置背面剔除 逆时针绘制为正面
//glEnable(GL_CULL_FACE);
//glCullFace(GL_BACK);

//设置只绘制线条
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

unsigned int VAO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);

unsigned int VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

unsigned int EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

unsigned int vertexShader;
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);

unsigned int fragmentShader;
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);

unsigned int shaderProgram;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);


//与layout(location=0)中 lacation 缓冲区位置一样（0-15）
//位置属性
glVertexAttribPointer(15, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(15);



while (!glfwWindowShouldClose(window))
{
	processInput(window);
	glfwPollEvents();
	glClearColor(0.0, 1.0, 1.0, 1.0);
	glClear(GL_COLOR_BUFFER_BIT);

	//CPU 通过 uniform 传递颜色到fragmentShader
	glBindVertexArray(VAO);
	float timeValue = glfwGetTime();
	float greenValue = (sin(timeValue) / 2.0f) + 0.5f;
	int vertexColorLocation = glGetUniformLocation(shaderProgram, "ourColor");
	glUseProgram(shaderProgram);
	glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f);
	glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);


	glfwSwapBuffers(window);

}
//结束绘制
glfwTerminate();
return 0;

}

void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
glfwSetWindowShouldClose(window, true);
}
}