OpenGL高级光照篇--SSAO-38

学习链接：中文 -------- 英语原文

这一节东西比较多，可以说对之前学过的内容的总结和练习。
多处使用帧缓冲，需要好好理解每个帧缓冲渲染的目的，渲染的结果存到哪了，输入是哪个帧缓冲的。
还是多看看代码和上面的文章。
文章底部还有其他的关于SSAO的介绍。

流程：
1.正常渲染GBuffer
2.渲染遮挡值
3.模糊遮挡值
4.应用遮挡到环境光上，其他光照正常计算（在观察空间）

源码：源码

自己跟着敲的一边代码：添加了部分注释

#include 
#include 
#include 

#include 
#include 
#include 

#include 
#include 
#include 

#include 
#include 

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow* window);
unsigned int loadTexture(const char* path, bool gammaCorrection);
void renderQuad();
void renderCube();

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
bool bloom = true;
bool bloomKeyPressed = false;
float exposure = 1.0f;

// camera
Camera camera(glm::vec3(0.0f, 0.0f, 5.0f));
float lastX = (float)SCR_WIDTH / 2.0;
float lastY = (float)SCR_HEIGHT / 2.0;
bool firstMouse = true;

// timing
float deltaTime = 0.0f;
float lastFrame = 0.0f;

float lerp(float a, float b, float t)
{
	return a + t * (b - a);
}

int main()
{
	// glfw: initialize and configure
	// ------------------------------
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
	glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

	// glfw window creation
	// --------------------
	GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);
	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	// tell GLFW to capture our mouse
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	// glad: load all OpenGL function pointers
	// ---------------------------------------
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	//stbi_set_flip_vertically_on_load(true);

	// configure global opengl state
	// -----------------------------
	glEnable(GL_DEPTH_TEST);

	//build and compile shaders
	Shader shaderGeometryPass("Shaders/Learn38_SSAOGeometry.vs", "Shaders/Learn38_SSAOGeometry.fs");
	Shader shaderLightingPass("Shaders/Learn38_SSAO.vs", "Shaders/Learn38_SSAOLighting.fs");
	Shader shaderSSAO("Shaders/Learn38_SSAO.vs", "Shaders/Learn38_SSAO.fs");
	Shader shaderSSAOBlur("Shaders/Learn38_SSAO.vs", "Shaders/Learn38_SSAOBlur.fs");

	//load model
	Model backpack("Models/backpack/backpack.obj");

	//configure gbuffer framebuffer;
	unsigned int gBuffer;
	glGenFramebuffers(1, &gBuffer);
	glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
	unsigned int gPosition, gNormal, gAlbedo;
	//position color buffer
	glGenTextures(1, &gPosition);
	glBindTexture(GL_TEXTURE_2D, gPosition);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGBA, GL_FLOAT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gPosition, 0);
	//normal color buffer
	glGenTextures(1, &gNormal);
	glBindTexture(GL_TEXTURE_2D, gNormal);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGBA, GL_FLOAT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, gNormal, 0);
	//color + specular color buffer
	glGenTextures(1, &gAlbedo);
	glBindTexture(GL_TEXTURE_2D, gAlbedo);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, gAlbedo, 0);
	//tell opengl which color attachments we'll use(of this framebuffer) for rendering
	unsigned int attacments[3] = { GL_COLOR_ATTACHMENT0,GL_COLOR_ATTACHMENT1,GL_COLOR_ATTACHMENT2 };
	glDrawBuffers(3, attacments);
	//create and attach depth buffer(renderbuffer)
	unsigned int rboDepth;
	glGenRenderbuffers(1, &rboDepth);
	glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, SCR_WIDTH, SCR_HEIGHT);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
	//finally check if framebuffer is complete
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
	{
		std::cout << "framebuffer not complete!" << std::endl;
	}
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	//also create framebuffer to hold SSAO processing stage
	unsigned int ssaoFBO, ssaoBlurFBO;
	glGenFramebuffers(1, &ssaoFBO);
	glGenFramebuffers(1, &ssaoBlurFBO);
	glBindFramebuffer(GL_FRAMEBUFFER, ssaoFBO);
	unsigned int ssaoColorBuffer, ssaoColorBufferBlur;
	//SSAO color buffer
	glGenTextures(1, &ssaoColorBuffer);
	glBindTexture(GL_TEXTURE_2D, ssaoColorBuffer);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, SCR_WIDTH, SCR_HEIGHT, 0, GL_RED, GL_FLOAT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ssaoColorBuffer, 0);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
	{
		std::cout << "SSAO Framebuffer not complete!" << std::endl;
	}
	//and blur stage
	glBindFramebuffer(GL_FRAMEBUFFER, ssaoBlurFBO);
	glGenTextures(1, &ssaoColorBufferBlur);
	glBindTexture(GL_TEXTURE_2D, ssaoColorBufferBlur);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, SCR_WIDTH, SCR_HEIGHT, 0, GL_RED, GL_FLOAT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ssaoColorBufferBlur, 0);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
	{
		std::cout << "SSAO blur framebuffer not complete!" << std::endl;
	}
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	//generate sample kernel
	std::uniform_real_distribution<GLfloat> randomFloats(0.0, 1.0);
	std::default_random_engine generator;
	std::vector<glm::vec3> ssaoKernel;
	for (unsigned int i = 0; i < 64; i++)
	{
		glm::vec3 sample(randomFloats(generator) * 2.0 - 1.0, randomFloats(generator) * 2.0 - 1.0, randomFloats(generator));
		sample = glm::normalize(sample);
		sample *= randomFloats(generator);
		float scale = float(i) / 64.0;

		//scale samples they're more aligned to center of kernel
		scale = lerp(0.1f, 1.0f, scale * scale);
		sample *= scale;
		ssaoKernel.push_back(sample);
	}

	//generate noise texture
	std::vector<glm::vec3> ssaoNoise;
	for (unsigned int i = 0; i < 16; i++)
	{
		glm::vec3 noise(randomFloats(generator) * 2.0 - 1.0, randomFloats(generator) * 2.0 - 1.0, 0.0f);
		ssaoNoise.push_back(noise);
	}
	unsigned int noiseTexture;
	glGenTextures(1, &noiseTexture);
	glBindTexture(GL_TEXTURE_2D, noiseTexture);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, 4, 4, 0, GL_RGB, GL_FLOAT, &ssaoNoise[0]);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

	//lighting info
	glm::vec3 lightPos = glm::vec3(2.0, 4.0, -2.0);
	glm::vec3 lightColor = glm::vec3(0.2, 0.2, 0.7);

	//shader configure
	shaderLightingPass.use();
	shaderLightingPass.setInt("gPosition", 0);
	shaderLightingPass.setInt("gNormal", 1);
	shaderLightingPass.setInt("gAlbedo", 2);
	shaderLightingPass.setInt("ssao", 3);

	shaderSSAO.use();
	shaderSSAO.setInt("gPosition", 0);
	shaderSSAO.setInt("gNormal", 1);
	shaderSSAO.setInt("texNoise", 2);

	shaderSSAOBlur.use();
	shaderSSAOBlur.setInt("ssaoInput", 0);

	// render loop	
	while (!glfwWindowShouldClose(window))
	{
		//per-frame time logic
		float currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;

		//input
		processInput(window);

		//render
		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
				
		//1.geometry pass :render scene's geometry/color data into gbuffer
		glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 50.0f);
		glm::mat4 view = camera.GetViewMatrix();
		glm::mat4 model = glm::mat4(1.0f);
		shaderGeometryPass.use();
		shaderGeometryPass.setMat4("projection", projection);
		shaderGeometryPass.setMat4("view", view);

		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(0.0f, 7.0f, 0.0f));
		model = glm::scale(model, glm::vec3(7.5f, 7.5f, 7.5f));
		shaderGeometryPass.setMat4("model", model);
		shaderGeometryPass.setInt("invertedNormals", 1);
		renderCube();
		shaderGeometryPass.setInt("invertedNormals", 0);

		//backpack model on the floor
		model = glm::mat4(1.0f);
		model = glm::translate(model, glm::vec3(0.0f, 0.5f, 0.0f));
		model = glm::rotate(model, glm::radians(-90.0f), glm::vec3(1.0f, 0.0f, 0.0f));
		model = glm::scale(model, glm::vec3(1.0f));
		shaderGeometryPass.setMat4("model", model);
		backpack.Draw(shaderGeometryPass);

		glBindFramebuffer(GL_FRAMEBUFFER, 0);
		
		//2.generate ssao texture
		glBindFramebuffer(GL_FRAMEBUFFER, ssaoFBO);
		glClear(GL_COLOR_BUFFER_BIT);
		shaderSSAO.use();
		//send kernel+rotation
		for (unsigned int i = 0; i < 64; i++)
		{
			shaderSSAO.setVec3("samples[" + std::to_string(i) + "]", ssaoKernel[i]);
		}
		shaderSSAO.setMat4("projection", projection);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, gPosition);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, gNormal);
		glActiveTexture(GL_TEXTURE2);
		glBindTexture(GL_TEXTURE_2D, noiseTexture);
		renderQuad();
		glBindFramebuffer(GL_FRAMEBUFFER, 0);		

		//3.blur ssao texture to remove noise
		glBindFramebuffer(GL_FRAMEBUFFER, ssaoBlurFBO);
		glClear(GL_COLOR_BUFFER_BIT);
		shaderSSAOBlur.use();
		glActiveTexture(GL_TEXTURE0);
		//这里用的ssaoColorBuffer,是上面渲染好的数据，渲染到ssaoColorBufferBlur
		glBindTexture(GL_TEXTURE_2D, ssaoColorBuffer);
		renderQuad();
		glBindFramebuffer(GL_FRAMEBUFFER, 0);		

		//4.lighting pass:traditional deferred Blinn-Phong lighting with added screen-space ambient occlusion
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		shaderLightingPass.use();
		//send light relevant uniforms
		glm::vec3 lightPosView = glm::vec3(camera.GetViewMatrix() * glm::vec4(lightPos, 1.0f));
		shaderLightingPass.setVec3("light.Position", lightPosView);
		shaderLightingPass.setVec3("light.Color", lightColor);
		//update attenuaton parameters
		const float linear = 0.09f;
		const float quadratic = 0.032f;
		shaderLightingPass.setFloat("light.Linear", linear);
		shaderLightingPass.setFloat("light.Quadratic", quadratic);

		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, gPosition);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, gNormal);
		glActiveTexture(GL_TEXTURE2);
		glBindTexture(GL_TEXTURE_2D, gAlbedo);
		glActiveTexture(GL_TEXTURE3);
		//这里输入是模糊好的buffer:ssaoColorBufferBlur
		glBindTexture(GL_TEXTURE_2D, ssaoColorBufferBlur);
		//finally render quad
		renderQuad();

		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwTerminate();
	return 0;
}

// renderCube() renders a 1x1 3D cube in NDC.
// -------------------------------------------------
unsigned int cubeVAO = 0;
unsigned int cubeVBO = 0;
void renderCube()
{
	// initialize (if necessary)
	if (cubeVAO == 0)
	{
		float vertices[] = {
			// back face
			-1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
			 1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 1.0f, // top-right
			 1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 0.0f, // bottom-right         
			 1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 1.0f, // top-right
			-1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
			-1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 1.0f, // top-left
			// front face
			-1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 0.0f, // bottom-left
			 1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 0.0f, // bottom-right
			 1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 1.0f, // top-right
			 1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 1.0f, // top-right
			-1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 1.0f, // top-left
			-1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 0.0f, // bottom-left
			// left face
			-1.0f,  1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-right
			-1.0f,  1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 1.0f, // top-left
			-1.0f, -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-left
			-1.0f, -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-left
			-1.0f, -1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 0.0f, // bottom-right
			-1.0f,  1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-right
			// right face
			 1.0f,  1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-left
			 1.0f, -1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-right
			 1.0f,  1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 1.0f, // top-right         
			 1.0f, -1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-right
			 1.0f,  1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-left
			 1.0f, -1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 0.0f, // bottom-left     
			// bottom face
			-1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 1.0f, // top-right
			 1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 1.0f, // top-left
			 1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 0.0f, // bottom-left
			 1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 0.0f, // bottom-left
			-1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 0.0f, // bottom-right
			-1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 1.0f, // top-right
			// top face
			-1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 1.0f, // top-left
			 1.0f,  1.0f , 1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 0.0f, // bottom-right
			 1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 1.0f, // top-right     
			 1.0f,  1.0f,  1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 0.0f, // bottom-right
			-1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 1.0f, // top-left
			-1.0f,  1.0f,  1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 0.0f  // bottom-left        
		};
		glGenVertexArrays(1, &cubeVAO);
		glGenBuffers(1, &cubeVBO);
		// fill buffer
		glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
		glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
		// link vertex attributes
		glBindVertexArray(cubeVAO);
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
		glEnableVertexAttribArray(2);
		glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
		glBindBuffer(GL_ARRAY_BUFFER, 0);
		glBindVertexArray(0);
	}
	// render Cube
	glBindVertexArray(cubeVAO);
	glDrawArrays(GL_TRIANGLES, 0, 36);
	glBindVertexArray(0);
}

// renderQuad() renders a 1x1 XY quad in NDC
// -----------------------------------------
unsigned int quadVAO = 0;
unsigned int quadVBO;
void renderQuad()
{
	if (quadVAO == 0)
	{
		float quadVertices[] = {
			// positions        // texture Coords
			-1.0f,  1.0f, 0.0f, 0.0f, 1.0f,
			-1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
			 1.0f,  1.0f, 0.0f, 1.0f, 1.0f,
			 1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
		};
		// setup plane VAO
		glGenVertexArrays(1, &quadVAO);
		glGenBuffers(1, &quadVBO);
		glBindVertexArray(quadVAO);
		glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
		glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
	}
	glBindVertexArray(quadVAO);
	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
	glBindVertexArray(0);
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
		glfwSetWindowShouldClose(window, true);

	if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
		camera.ProcessKeyboard(FORWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
		camera.ProcessKeyboard(BACKWARD, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
		camera.ProcessKeyboard(LEFT, deltaTime);
	if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
		camera.ProcessKeyboard(RIGHT, deltaTime);

	if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS && !bloomKeyPressed)
	{
		bloom = !bloom;
		bloomKeyPressed = true;
	}
	if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_RELEASE)
	{
		bloomKeyPressed = false;
	}

	if (glfwGetKey(window, GLFW_KEY_Q) == GLFW_PRESS)
	{
		if (exposure > 0.0f)
			exposure -= 0.01f;
		else
			exposure = 0.0f;
	}
	else if (glfwGetKey(window, GLFW_KEY_E) == GLFW_PRESS)
	{
		exposure += 0.01f;
	}
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
	// make sure the viewport matches the new window dimensions; note that width and 
	// height will be significantly larger than specified on retina displays.
	glViewport(0, 0, width, height);
}

// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
	if (firstMouse)
	{
		lastX = xpos;
		lastY = ypos;
		firstMouse = false;
	}

	float xoffset = xpos - lastX;
	float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

	lastX = xpos;
	lastY = ypos;

	camera.ProcessMouseMovement(xoffset, yoffset);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	camera.ProcessMouseScroll(yoffset);
}

// utility function for loading a 2D texture from file
// ---------------------------------------------------
unsigned int loadTexture(char const* path, bool gammaCorrection)
{
	unsigned int textureID;
	glGenTextures(1, &textureID);

	int width, height, nrComponents;
	unsigned char* data = stbi_load(path, &width, &height, &nrComponents, 0);
	if (data)
	{
		GLenum internalFormat;
		GLenum dataFormat;
		if (nrComponents == 1)
		{
			internalFormat = dataFormat = GL_RED;
		}
		else if (nrComponents == 3)
		{
			internalFormat = gammaCorrection ? GL_SRGB : GL_RGB;
			dataFormat = GL_RGB;
		}
		else if (nrComponents == 4)
		{
			internalFormat = gammaCorrection ? GL_SRGB_ALPHA : GL_RGBA;
			dataFormat = GL_RGBA;
		}

		glBindTexture(GL_TEXTURE_2D, textureID);
		glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, width, height, 0, dataFormat, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		stbi_image_free(data);
	}
	else
	{
		std::cout << "Texture failed to load at path: " << path << std::endl;
		stbi_image_free(data);
	}

	return textureID;
}