todo: 关于切线空间的理解，还需要再多查一些资料，深入理解
这一章节看了好几天，涉及的细节较多，需要慢慢消化
一、SSAO原理
SSAO：Screen-Space Ambient Occlusion 屏幕空间环境光遮蔽
1. 为什么要用SSAO？
之前的章节里，环境光照都是采用默认值，全局相同。实际场景中，环境光复杂的反射，物体凹处应该会更阴暗，那如何实现这种阴暗的变化呢？SSAO就是解决这个问题，用一种近似的方法模拟环境光的相互作用。
使用SSAO对比
SSAO非常巧妙，并没有陷入光照的反射计算中，而是另辟蹊径，用非常低的成本模拟出了环境光变化。这里很有启发，做视觉并不是要100%还原真实场景，而是近似即可，如何近似，要跳出原理，从多种维度想办法，什么是技术？真是个拷问灵魂的问题。
2. SSAO的实现逻辑
实现原理和前面抗锯齿的理念有点像，随机取片段周边多个点，数这些点中可见的点的数量n，n作为环境光照的亮度权重
ssao计算原理
SSAO的原理不复杂，复杂的是需要不断优化，实现一个可用性高的采样算法
-
优化1，实际计算，用半球来采样，因为下半球几乎都不可见，反而会有干扰
优化1-半球采样
-
优化2，让采样点尽量靠近片段
优化2-加速插值函数
定义加速插值函数lerp
...[接上函数]
scale = lerp(0.1f, 1.0f, scale * scale);
sample *= scale;
ssaoKernel.push_back(sample);
}
// lerp被定义为：
GLfloat lerp(GLfloat a, GLfloat b, GLfloat f)
{
return a + f * (b - a);
}
- 优化3， 随机核心转动，生成一张转动的纹理，并放大成一个屏幕的大小，随机的去影响采样点
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
记得采样属性里设置REPEAT，让4x4的扰动纹理repeat到整个屏幕空间
std::vector<glm::vec3> ssaoNoise;
for (GLuint 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);
}
二、代码实现流程
整个渲染流程，和GPUimage的逻辑类似，形成一个渲染管道，不断的在帧缓冲中离屏渲染生成需要的纹理。
实现流程图
1. 参考之前的延迟渲染，用3个g-buffer，最终生成一个2D纹理
- 第一个g-buffer：生成depth normal albedo
- 第二个g-buffer ssaoFBO：基于第一个gbuffer产物生成环境光遮罩纹理
- 第三个g-buffer ssaoBlurFBO：基于第二个gbuffer产物进行模糊处理，去掉毛刺噪点，图像看起来更平滑
2. 简单的模糊处理
取周边4 x 4的空间纹理，取平均数，简单实用，也可以用高斯模糊。注意代码里怎么取4 x 4的纹理，通过计算纹理大小，取4份。
另外，按照下面这个算法，当前点并不是4x4的中心点，最好是取5x5的，这样中间点是(0, 0)
void main() {
vec2 texelSize = 1.0 / vec2(textureSize(ssaoInput, 0));
float result = 0.0;
for (int x = -2; x < 2; ++x)
{
for (int y = -2; y < 2; ++y)
{
vec2 offset = vec2(float(x), float(y)) * texelSize;
result += texture(ssaoInput, TexCoords + offset).r;
}
}
fragColor = result / (4.0 * 4.0);
}
3. 最终的光照计算
vec3 ambient = vec3(0.3 * AmbientOcclusion); // <-- this is where we use ambient occlusion
和之前的光照渲染区别在于，增加了环境光遮蔽因子，体现明暗特点
实现效果
三、源码参考：
一共有三对shader，其中ssao.vs是共用的普通顶点着色器
- 几何： ssao_peometry.vs ssao_geometry.fs
- SSAO： ssao.vs ssao.fs
- 模糊： ssao.vs ssao_blur.fs
- 光照： ssao.vs ssao_lighting.fs
ssao_peometry
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 texCoords;
out vec3 FragPos;
out vec2 TexCoords;
out vec3 Normal;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
vec4 viewPos = view * model * vec4(position, 1.0f);
FragPos = viewPos.xyz;
gl_Position = projection * viewPos;
TexCoords = texCoords;
mat3 normalMatrix = transpose(inverse(mat3(view * model)));
Normal = normalMatrix * normal;
}
ssao_geometry.fs
#version 330 core
layout (location = 0) out vec4 gPositionDepth;
layout (location = 1) out vec3 gNormal;
layout (location = 2) out vec4 gAlbedoSpec;
in vec2 TexCoords;
in vec3 FragPos;
in vec3 Normal;
const float NEAR = 0.1; // Projection matrix's near plane distance
const float FAR = 50.0f; // Projection matrix's far plane distance
float LinearizeDepth(float depth)
{
float z = depth * 2.0 - 1.0; // Back to NDC
return (2.0 * NEAR * FAR) / (FAR + NEAR - z * (FAR - NEAR));
}
void main()
{
// Store the fragment position vector in the first gbuffer texture
gPositionDepth.xyz = FragPos;
// And store linear depth into gPositionDepth's alpha component
gPositionDepth.a = LinearizeDepth(gl_FragCoord.z); // Divide by FAR if you need to store depth in range 0.0 - 1.0 (if not using floating point colorbuffer)
// Also store the per-fragment normals into the gbuffer
gNormal = normalize(Normal);
// And the diffuse per-fragment color
gAlbedoSpec.rgb = vec3(0.95); // Currently all objects have constant albedo color
}
ssao.vs
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec2 texCoords;
out vec2 TexCoords;
void main()
{
gl_Position = vec4(position, 1.0f);
TexCoords = texCoords;
}
ssao.fs
#version 330 core
out float FragColor;
in vec2 TexCoords;
uniform sampler2D gPositionDepth;
uniform sampler2D gNormal;
uniform sampler2D texNoise;
uniform vec3 samples[64];
// parameters (you'd probably want to use them as uniforms to more easily tweak the effect)
int kernelSize = 64;
float radius = 1.0;
// tile noise texture over screen based on screen dimensions divided by noise size
const vec2 noiseScale = vec2(800.0f/4.0f, 600.0f/4.0f);
uniform mat4 projection;
void main()
{
// Get input for SSAO algorithm
vec3 fragPos = texture(gPositionDepth, TexCoords).xyz;
vec3 normal = texture(gNormal, TexCoords).rgb;
vec3 randomVec = texture(texNoise, TexCoords * noiseScale).xyz;
// Create TBN change-of-basis matrix: from tangent-space to view-space
vec3 tangent = normalize(randomVec - normal * dot(randomVec, normal));
vec3 bitangent = cross(normal, tangent);
mat3 TBN = mat3(tangent, bitangent, normal);
// Iterate over the sample kernel and calculate occlusion factor
float occlusion = 0.0;
for(int i = 0; i < kernelSize; ++i)
{
// get sample position
vec3 sample = TBN * samples[i]; // From tangent to view-space
sample = fragPos + sample * radius;
// project sample position (to sample texture) (to get position on screen/texture)
vec4 offset = vec4(sample, 1.0);
offset = projection * offset; // from view to clip-space
// offset.w应该是1，这里做通用性处理，/1
offset.xyz /= offset.w; // perspective divide
offset.xyz = offset.xyz * 0.5 + 0.5; // transform to range 0.0 - 1.0
// get sample depth
float sampleDepth = texture(gPositionDepth, offset.xy).w; // Get depth value of kernel sample
// range check & accumulate
float rangeCheck = smoothstep(0.0, 1.0, radius / abs(fragPos.z - sampleDepth ));
occlusion += (sampleDepth >= sample.z ? 1.0 : 0.0) * rangeCheck;
}
occlusion = 1.0 - (occlusion / kernelSize);
FragColor = occlusion;
}
ssao_blur.fs
#version 330 core
in vec2 TexCoords;
out float fragColor;
uniform sampler2D ssaoInput;
const int blurSize = 4; // use size of noise texture (4x4)
void main()
{
vec2 texelSize = 1.0 / vec2(textureSize(ssaoInput, 0));
float result = 0.0;
for (int x = 0; x < blurSize; ++x)
{
for (int y = 0; y < blurSize; ++y)
{
vec2 offset = (vec2(-2.0) + vec2(float(x), float(y))) * texelSize;
result += texture(ssaoInput, TexCoords + offset).r;
}
}
fragColor = result / float(blurSize * blurSize);
}
ssao_lighting.fs
#version 330 core
out vec4 FragColor;
in vec2 TexCoords;
uniform sampler2D gPositionDepth;
uniform sampler2D gNormal;
uniform sampler2D gAlbedo;
uniform sampler2D ssao;
struct Light {
vec3 Position;
vec3 Color;
float Linear;
float Quadratic;
};
uniform Light light;
void main()
{
// Retrieve data from g-buffer
vec3 FragPos = texture(gPositionDepth, TexCoords).rgb;
vec3 Normal = texture(gNormal, TexCoords).rgb;
vec3 Diffuse = texture(gAlbedo, TexCoords).rgb;
float AmbientOcclusion = texture(ssao, TexCoords).r;
// Then calculate lighting as usual
vec3 ambient = vec3(0.3 * AmbientOcclusion); // <-- this is where we use ambient occlusion
vec3 lighting = ambient;
vec3 viewDir = normalize(-FragPos); // Viewpos is (0.0.0)
// Diffuse
vec3 lightDir = normalize(light.Position - FragPos);
vec3 diffuse = max(dot(Normal, lightDir), 0.0) * Diffuse * light.Color;
// Specular
vec3 halfwayDir = normalize(lightDir + viewDir);
float spec = pow(max(dot(Normal, halfwayDir), 0.0), 8.0);
vec3 specular = light.Color * spec;
// Attenuation
float distance = length(light.Position - FragPos);
float attenuation = 1.0 / (1.0 + light.Linear * distance + light.Quadratic * distance * distance);
diffuse *= attenuation;
specular *= attenuation;
lighting += diffuse + specular;
FragColor = vec4(lighting, 1.0);
}
主程序：main.cpp
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "Shader.h"
#include "camera.h"
#include "model.h"
#include <iostream>
#include <random>
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);
unsigned int loadCubemap(vector<std::string> faces);
void renderScene (const Shader &shader);
void renderCube();
void RenderQuad();
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
bool blinn = false;
bool blinnKeyPressed = false;
bool gammaEnabled = true;
bool gammaKeyPressed = false;
bool bloom = true;
bool hdr = true; //change with 'space'
float exposure = 1.0f; // change with Q and E
// 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;
unsigned int draw_mode = 1;
float lerp(float a, float b, float f)
{
return a + f * (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, "天哥学opengl", 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;
}
// glPolygonMode(GL_FRONT_AND_BACK ,GL_LINE );
// configure global opengl state
// -----------------------------
glEnable(GL_DEPTH_TEST);
// build and compile shaders
// -------------------------
Shader shaderGeometryPass("ssao_geometry.vs", "ssao_geometry.fs");
Shader shaderLightingPass("ssao.vs", "ssao_lighting.fs");
Shader shaderSSAO("ssao.vs", "ssao.fs");
Shader shaderSSAOBlur("ssao.vs", "ssao_blur.fs");
// Set samplers
shaderLightingPass.Use();
glUniform1i(glGetUniformLocation(shaderLightingPass.Program, "gPositionDepth"), 0);
glUniform1i(glGetUniformLocation(shaderLightingPass.Program, "gNormal"), 1);
glUniform1i(glGetUniformLocation(shaderLightingPass.Program, "gAlbedo"), 2);
glUniform1i(glGetUniformLocation(shaderLightingPass.Program, "ssao"), 3);
shaderSSAO.Use();
glUniform1i(glGetUniformLocation(shaderSSAO.Program, "gPositionDepth"), 0);
glUniform1i(glGetUniformLocation(shaderSSAO.Program, "gNormal"), 1);
glUniform1i(glGetUniformLocation(shaderSSAO.Program, "texNoise"), 2);
// Objects
Model nanosuit("pack/backpack.obj");
// Lights
glm::vec3 lightPos = glm::vec3(2.0, 4.0, -2.0);
glm::vec3 lightColor = glm::vec3(0.2, 0.2, 0.7);
// Set up G-Buffer
// 3 textures:
// 1. Positions + depth (RGBA)
// 2. Color (RGB)
// 3. Normals (RGB)
GLuint gBuffer;
glGenFramebuffers(1, &gBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, gBuffer);
GLuint gPositionDepth, gNormal, gAlbedo;
// - Position + linear depth color buffer
glGenTextures(1, &gPositionDepth);
glBindTexture(GL_TEXTURE_2D, gPositionDepth);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, 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, gPositionDepth, 0);
// - Normal color buffer
glGenTextures(1, &gNormal);
glBindTexture(GL_TEXTURE_2D, gNormal);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, SCR_WIDTH, SCR_HEIGHT, 0, GL_RGB, 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);
// - Albedo color buffer
glGenTextures(1, &gAlbedo);
glBindTexture(GL_TEXTURE_2D, gAlbedo);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 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_ATTACHMENT2, GL_TEXTURE_2D, gAlbedo, 0);
// - Tell OpenGL which color attachments we'll use (of this framebuffer) for rendering
GLuint attachments[3] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2 };
glDrawBuffers(3, attachments);
// - Create and attach depth buffer (renderbuffer)
GLuint 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 << "GBuffer Framebuffer not complete!" << std::endl;
// Also create framebuffer to hold SSAO processing stage
GLuint ssaoFBO, ssaoBlurFBO;
glGenFramebuffers(1, &ssaoFBO); glGenFramebuffers(1, &ssaoBlurFBO);
glBindFramebuffer(GL_FRAMEBUFFER, ssaoFBO);
GLuint 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_RGB, 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_RGB, 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);
// Sample kernel
std::uniform_real_distribution<GLfloat> randomFloats(0.0, 1.0); // generates random floats between 0.0 and 1.0
std::default_random_engine generator;
std::vector<glm::vec3> ssaoKernel;
// 生成采样核，在一个圆内生成随机的64个点坐标
for (GLuint i = 0; i < 64; ++i)
{
// 随机点的x y 坐标 [-1, 1]，x y决定方向的随机
glm::vec3 sample(randomFloats(generator) * 2.0 - 1.0, randomFloats(generator) * 2.0 - 1.0, randomFloats(generator));
// 生成随机长度
// 1）标准化，使半径为1
// 2）乘1个[0,1]的随机数，半径随机为一个小于1的数
// 乘一个lerp(i/64)函数，增加半径的长度变化，使长短分布更均匀
sample = glm::normalize(sample);
sample *= randomFloats(generator);
GLfloat scale = GLfloat(i) / 64.0;
// Scale samples s.t. they're more aligned to center of kernel
scale = lerp(0.1f, 1.0f, scale * scale);
sample *= scale;
ssaoKernel.push_back(sample);
}
// Noise texture
std::vector<glm::vec3> ssaoNoise;
for (GLuint i = 0; i < 16; i++)
{
glm::vec3 noise(randomFloats(generator) * 2.0 - 1.0, randomFloats(generator) * 2.0 - 1.0, 0.0f); // rotate around z-axis (in tangent space)
ssaoNoise.push_back(noise);
}
GLuint noiseTexture; glGenTextures(1, &noiseTexture);
glBindTexture(GL_TEXTURE_2D, noiseTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, 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);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
while (!glfwWindowShouldClose(window)) {
float currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
processInput(window);
glClearColor(0.05f, 0.05f, 0.05f, 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(camera.Zoom, (GLfloat)SCR_WIDTH / (GLfloat)SCR_HEIGHT, 0.1f, 50.0f);
glm::mat4 view = camera.GetViewMatrix();
glm::mat4 model;
shaderGeometryPass.Use();
glUniformMatrix4fv(glGetUniformLocation(shaderGeometryPass.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
glUniformMatrix4fv(glGetUniformLocation(shaderGeometryPass.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
// Floor cube
model = glm::translate(model, glm::vec3(0.0, -1.1f, 0.0f));
model = glm::scale(model, glm::vec3(20.0f, 1.0f, 20.0f));
glUniformMatrix4fv(glGetUniformLocation(shaderGeometryPass.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
renderCube();
// Nanosuit model on the floor
model = glm::mat4();
model = glm::translate(model, glm::vec3(0.0f, 0.0f, 5.0));
model = glm::rotate(model, glm::radians(-90.0f), glm::vec3(1.0, 0.0, 0.0));
model = glm::scale(model, glm::vec3(0.5f));
glUniformMatrix4fv(glGetUniformLocation(shaderGeometryPass.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
nanosuit.Draw(shaderGeometryPass);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 2. Create SSAO texture
glBindFramebuffer(GL_FRAMEBUFFER, ssaoFBO);
glClear(GL_COLOR_BUFFER_BIT);
shaderSSAO.Use();
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, gPositionDepth);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, gNormal);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, noiseTexture);
// Send kernel + rotation
for (GLuint i = 0; i < 64; ++i)
glUniform3fv(glGetUniformLocation(shaderSSAO.Program, ("samples[" + std::to_string(i) + "]").c_str()), 1, &ssaoKernel[i][0]);
glUniformMatrix4fv(glGetUniformLocation(shaderSSAO.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
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);
glBindTexture(GL_TEXTURE_2D, ssaoColorBuffer);
RenderQuad();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 4. Lighting Pass: traditional deferred Blinn-Phong lighting now with added screen-space ambient occlusion
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
shaderLightingPass.Use();
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, gPositionDepth);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, gNormal);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, gAlbedo);
glActiveTexture(GL_TEXTURE3); // Add extra SSAO texture to lighting pass
glBindTexture(GL_TEXTURE_2D, ssaoColorBufferBlur);
// Also send light relevant uniforms
glm::vec3 lightPosView = glm::vec3(camera.GetViewMatrix() * glm::vec4(lightPos, 1.0));
glUniform3fv(glGetUniformLocation(shaderLightingPass.Program, "light.Position"), 1, &lightPosView[0]);
glUniform3fv(glGetUniformLocation(shaderLightingPass.Program, "light.Color"), 1, &lightColor[0]);
// Update attenuation parameters
const GLfloat constant = 1.0; // Note that we don't send this to the shader, we assume it is always 1.0 (in our case)
const GLfloat linear = 0.09;
const GLfloat quadratic = 0.032;
glUniform1f(glGetUniformLocation(shaderLightingPass.Program, "light.Linear"), linear);
glUniform1f(glGetUniformLocation(shaderLightingPass.Program, "light.Quadratic"), quadratic);
glUniform1i(glGetUniformLocation(shaderLightingPass.Program, "draw_mode"), draw_mode);
RenderQuad();
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
bool startRecord = false;
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_1) == GLFW_PRESS) {
draw_mode = 1;
}
if (glfwGetKey(window, GLFW_KEY_2) == GLFW_PRESS) {
draw_mode = 2;
}
if (glfwGetKey(window, GLFW_KEY_3) == GLFW_PRESS) {
draw_mode = 3;
}
if (glfwGetKey(window, GLFW_KEY_4) == GLFW_PRESS) {
draw_mode = 4;
}
if (glfwGetKey(window, GLFW_KEY_B) == GLFW_PRESS && !gammaKeyPressed)
{
gammaEnabled = !gammaEnabled;
gammaKeyPressed = true;
}
if (glfwGetKey(window, GLFW_KEY_B) == GLFW_RELEASE)
{
gammaKeyPressed = false;
}
if (glfwGetKey(window, GLFW_KEY_Y))
{
std::cout << "Y" << std::endl;
startRecord = true;
firstMouse = true;
}
if (glfwGetKey(window, GLFW_KEY_N))
{
std::cout << "N" << std::endl;
startRecord = false;
}
if (startRecord) {
return;
}
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_Q) == GLFW_PRESS)
exposure -= 0.5 * deltaTime;
if (glfwGetKey(window, GLFW_KEY_E) == GLFW_PRESS)
exposure += 0.5 * deltaTime;
if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS && !gammaKeyPressed)
{
hdr = !hdr;
gammaKeyPressed = true;
}
if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_RELEASE)
{
gammaKeyPressed = false;
}
}
// 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)
{
// std::cout << "xpos : " << xpos << std::endl;
// std::cout << "ypos : " << ypos << std::endl;
if (startRecord) {
return;
}
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;
// std::cout << "xoffset : " << xoffset << std::endl;
// std::cout << "yoffset : " << yoffset << std::endl;
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)
{
unsigned int textureID;
glGenTextures(1, &textureID);
int width, height, nrComponents;
unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
if (data)
{
GLenum format;
if (nrComponents == 1)
format = GL_RED;
else if (nrComponents == 3)
format = GL_RGB;
else if (nrComponents == 4)
format = GL_RGBA;
glBindTexture(GL_TEXTURE_2D, textureID);
glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, 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;
}
unsigned int loadCubemap(vector<std::string> faces)
{
unsigned int textureID;
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
int width, height, nrChannels;
for (unsigned int i = 0; i < faces.size(); i++) {
unsigned char *data = stbi_load(faces[i].c_str(), &width, &height, &nrChannels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
stbi_image_free(data);
}
else
{
std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
stbi_image_free(data);
}
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
}
return textureID;
}
void renderScene(const Shader &shader)
{
// room cube
glm::mat4 model = glm::mat4(1.0f);
model = glm::scale(model, glm::vec3(5.0f));
shader.setMat4("model", model);
glDisable(GL_CULL_FACE); // note that we disable culling here since we render 'inside' the cube instead of the usual 'outside' which throws off the normal culling methods.
shader.setInt("reverse_normals", 1); // A small little hack to invert normals when drawing cube from the inside so lighting still works.
renderCube();
shader.setInt("reverse_normals", 0); // and of course disable it
glEnable(GL_CULL_FACE);
// cubes
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(4.0f, -3.5f, 0.0));
model = glm::scale(model, glm::vec3(0.5f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(2.0f, 3.0f, 1.0));
model = glm::scale(model, glm::vec3(0.75f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(-3.0f, -1.0f, 0.0));
model = glm::scale(model, glm::vec3(0.5f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(-1.5f, 1.0f, 1.5));
model = glm::scale(model, glm::vec3(0.5f));
shader.setMat4("model", model);
renderCube();
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(-1.5f, 2.0f, -3.0));
model = glm::rotate(model, glm::radians(60.0f), glm::normalize(glm::vec3(1.0, 0.0, 1.0)));
model = glm::scale(model, glm::vec3(0.75f));
shader.setMat4("model", model);
renderCube();
}
// 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);
}
glBindVertexArray(cubeVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);
}
// RenderQuad() Renders a 1x1 quad in NDC
unsigned int quadVAO = 0;
unsigned int quadVBO;
void RenderQuad()
{
if (quadVAO == 0)
{
GLfloat 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(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
}
glBindVertexArray(quadVAO);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glBindVertexArray(0);
}
网友评论