一、原理介绍
HDR：High Dynamic Range, 高动态范围
LDR： Low Dynamic Range, 低动态范围
1. 为什么有HDR？
过度曝光
屏幕显示颜色会约束到[0,1]之间，如果场景中有很多超过1的color值，比如10、15、100都会约束到1，体现不出真实的纹理。
HDR技术通过一个颜色映射，把大范围的值缩放到一个小范围内。尽量体现场景中高亮度和低亮度的纹理细节。HDR映射有很多算法，没有绝对的优劣，只有侧重，有的侧重高亮细节，有的侧重灰暗细节
HDR映射
2. 实现流程
- 把场景渲染到自定义的帧缓冲，帧缓冲可以设置color的取值范围，默认的窗口缓冲不支持设置精度，默认是一个字节8位，自定义缓冲可以设置16或32位浮点类型。另外，即使默认的缓冲支持设置数据类型，最好也通过自定义帧缓冲生成一张2维纹理，最后只需要针对2维纹理做映射计算，性能上有数量级的提升
- 切回到默认缓冲，把帧缓冲渲染到默认窗口，同时，在shader中增加Reinhard(混合渲染)色调映射算法，调整颜色范围
3.核心代码说明，完整代码在文末
3.1 设计一个拉长的立方体，注意法线要朝里边，因为我们要从里面观察纹理
// render tunne;
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(0.0f,0.0f, 25.0));
// 按原教程的缩放有点问题
// model = glm::scale(model, glm::vec3(5.0f, 5.0f, 55.0f));
model = glm::scale(model, glm::vec3(2.5f, 2.5f, 27.5f));
shader.setMat4("model", model);
shader.setBool("inverse_normals", true);
3.2 渲染到帧缓冲，帧缓冲的代码不复杂，但是有点啰嗦，这里不贴了，参看文末代码，有一点注意，原教程中没有设置纹理为“0”,看起来默认为0的纹理，不用设置？
// shader.use();
// shader.setInt("diffuseTexture", 0);
// hdrShader.use();
// hdrShader.setInt("hdrBuffer", 0);
3.3 绘制到默认窗口，也不复杂：略
3.4 渲染到默认窗口的着色器中，有个最简单的算法，把所有颜色约束到[0,1]之间，突出低亮度部分，兼顾高亮度部分
// reinhard
vec3 result = hdrColor / (hdrColor + vec3(1.0));
算法函数
4. 实现效果
HDR效果
二、曝光算法
通过曝光度来控制映射曲线
上面讲的混合渲染算法简单通用，但是没有个特性化的参数调整，比如，我就想整体偏亮一点，想曝光高一点呢。实现算法在片段着色其中，算法公式：
曝光函数
曝光度越大，映射曲线越陡峭，场景越亮，缺点是在非常高亮的点非常接近，体现不出纹理的细节差别，真实的摄影后期处理中，要根据个人需求的侧重点，不断调参。
曝光度= 1
曝光度 = 6
实现效果
代码改动量不大，基于上面的混合渲染，修改下片段着色器中的color result计算即可
曝光度变化
void main()
{
const float gamma = 2.2;
vec3 hdrColor = texture(hdrBuffer, TexCoords).rgb;
// reinhard
//vec3 result = hdrColor / (hdrColor + vec3(1.0));
vec3 result = vec3(1.0) - exp(-hdrColor * exposure);
// also gamma correct while we're at it
result = pow(result, vec3(1.0 / gamma));
color = vec4(result, 1.0f);
}
三、完整代码
HDR .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;
}
HDR .fs
#version 330 core
out vec4 color;
in vec2 TexCoords;
uniform sampler2D hdrBuffer;
uniform float exposure;
uniform bool hdr;
void main()
{
const float gamma = 2.2;
vec3 hdrColor = texture(hdrBuffer, TexCoords).rgb;
// reinhard
vec3 result = hdrColor / (hdrColor + vec3(1.0));
// vec3 result = vec3(1.0) - exp(-hdrColor * exposure);
// also gamma correct while we're at it
result = pow(result, vec3(1.0 / gamma));
color = vec4(result, 1.0f);
}
默认窗口的渲染 .vs 没有特殊逻辑
#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;
}
默认窗口的渲染 .fs 最核心的逻辑
#version 330 core
out vec4 color;
in vec2 TexCoords;
uniform sampler2D hdrBuffer;
uniform float exposure;
uniform bool hdr;
void main()
{
const float gamma = 2.2;
vec3 hdrColor = texture(hdrBuffer, TexCoords).rgb;
// reinhard
vec3 result = hdrColor / (hdrColor + vec3(1.0));
// vec3 result = vec3(1.0) - exp(-hdrColor * exposure);
// also gamma correct while we're at it
result = pow(result, vec3(1.0 / gamma));
color = vec4(result, 1.0f);
}
主程序
#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>
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;
// camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
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;
bool hdr = true; //change with 'space'
float exposure = 1.0f; // change with Q and E
unsigned int woodTexture;
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 shader("1.lighting.vs", "1.lighting.fs");
Shader hdrShader("1.colors.vs", "1.colors.fs");
// Light sources
// Positions
std::vector<glm::vec3> lightPositions;
lightPositions.push_back(glm::vec3(0.0f, 0.0f, 49.5f)); //back light
lightPositions.push_back(glm::vec3(-1.4f, -1.9f, 9.0f));
lightPositions.push_back(glm::vec3(0.0f, -1.8f, 4.0f));
lightPositions.push_back(glm::vec3(0.8f, -1.7f, 6.0f));
// -Colors
std::vector<glm::vec3> lightColors;
lightColors.push_back(glm::vec3(200.0f, 200.0f, 200.0f));
lightColors.push_back(glm::vec3(0.1f, 0.0f, 0.0f));
lightColors.push_back(glm::vec3(0.0f, 0.0f, 0.2f));
lightColors.push_back(glm::vec3(0.0f, 0.1f, 0.0f));
// Load textures
woodTexture = loadTexture("resource/wood.png");
unsigned int hdrFBO;
glGenFramebuffers(1, &hdrFBO);
unsigned int colorBuffer;
glGenTextures(1, &colorBuffer);
glBindTexture(GL_TEXTURE_2D, colorBuffer);
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_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// create depth buffer (renderbuffer)
unsigned int rboDepth;
glGenRenderbuffers(1, &rboDepth);
glBindRenderbuffer(GL_RENDERBUFFER, rboDepth);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, SCR_WIDTH, SCR_HEIGHT);
// - Attach buffers
glBindFramebuffer(GL_FRAMEBUFFER, hdrFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorBuffer,0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rboDepth);
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
std::cout << "Framebuffer not complete!" << std::endl;
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
// shader.use();
// shader.setInt("diffuseTexture", 0);
// hdrShader.use();
// hdrShader.setInt("hdrBuffer", 0);
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
float currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
processInput(window);
glBindFramebuffer(GL_FRAMEBUFFER, hdrFBO);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glm::mat4 projection = glm::perspective(camera.Zoom, (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
glm::mat4 view = camera.GetViewMatrix();
glm::mat4 model;
shader.use();
shader.setMat4("projection", projection);
shader.setMat4("view", view);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, woodTexture);
// set lighting uniforms
for (unsigned int i = 0; i < lightPositions.size(); i++) {
shader.setVec3("lights[" + std::to_string(i) + "].Position", lightPositions[i]);
shader.setVec3("lights[" + std::to_string(i) + "].Color", lightColors[i]);
}
shader.setVec3("viewPos", camera.Position);
// render tunne;
model = glm::mat4(1.0f);
model = glm::translate(model, glm::vec3(0.0f,0.0f, 25.0));
// model = glm::scale(model, glm::vec3(5.0f, 5.0f, 55.0f));
model = glm::scale(model, glm::vec3(2.5f, 2.5f, 27.5f));
shader.setMat4("model", model);
shader.setBool("inverse_normals", true);
renderCube();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// 2. Now render floating point colorbuffer to 2D quad and tonemap HDR colors to default framebuffer's (clamped) color range
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
hdrShader.use();
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, colorBuffer);
hdrShader.setInt("hdr", hdr);
hdrShader.setFloat("exposure", exposure);
RenderQuad();
// std::cout << "exposure: " << exposure << std::endl;
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
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_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);
}
// render Cube
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);
}
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