openGL Lighting Maps

实现一些光照照射到object上的真实反射

main：

#include <iostream>
#include <cmath>

// GLEW
#define GLEW_STATIC
#include <glew.h>

// GLFW
#include <glfw3.h>

// Other Libs
#include <SOIL.h>
// GLM Mathematics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

// Other includes
#include "Shader.h"
#include "Camera.h"

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void do_movement();

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
GLfloat lastX = WIDTH / 2.0;
GLfloat lastY = HEIGHT / 2.0;
bool keys[1024];

// Light attributes
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);

// Deltatime
GLfloat deltaTime = 0.0f; // Time between current frame and last frame
GLfloat lastFrame = 0.0f; // Time of last frame

// The MAIN function, from here we start the application and run the game loop
int main()
{
// Init GLFW
glfwInit();
// Set all the required options for GLFW
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
glfwWindowHint(GLFW_SAMPLES, 4);

// Create a GLFWwindow object that we can use for GLFW's functions
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
glfwMakeContextCurrent(window);

// Set the required callback functions
glfwSetKeyCallback(window, key_callback);
glfwSetCursorPosCallback(window, mouse_callback);
glfwSetScrollCallback(window, scroll_callback);

// GLFW Options
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
glewExperimental = GL_TRUE;
// Initialize GLEW to setup the OpenGL Function pointers
glewInit();

// Define the viewport dimensions
glViewport(0, 0, WIDTH, HEIGHT);

// OpenGL options
glEnable(GL_DEPTH_TEST);

// Build and compile our shader program
Shader lightingShader("lighting.vs", "lighting.frag");
Shader lampShader("lamp.vs", "lamp.frag");

// Set up vertex data (and buffer(s)) and attribute pointers
GLfloat vertices[] = {
// Positions // Normals // Texture Coords
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,

-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,

-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,

-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f
};
// First, set the container's VAO (and VBO)
GLuint VBO, containerVAO;
glGenVertexArrays(1, &containerVAO);
glGenBuffers(1, &VBO);

glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

glBindVertexArray(containerVAO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));
glEnableVertexAttribArray(2);
glBindVertexArray(0);

// Then, we set the light's VAO (VBO stays the same. After all, the vertices are the same for the light object (also a 3D cube))
GLuint lightVAO;
glGenVertexArrays(1, &lightVAO);
glBindVertexArray(lightVAO);
// We only need to bind to the VBO (to link it with glVertexAttribPointer), no need to fill it; the VBO's data already contains all we need.
glBindBuffer(GL_ARRAY_BUFFER, VBO);
// Set the vertex attributes (only position data for the lamp))
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0); // Note that we skip over the other data in our buffer object (we don't need the normals/textures, only positions).
glEnableVertexAttribArray(0);
glBindVertexArray(0);

// Load textures
GLuint diffuseMap, specularMap, emissionMap;
glGenTextures(1, &diffuseMap);
glGenTextures(1, &specularMap);
glGenTextures(1, &emissionMap);
int width, height;
unsigned char* image;
// Diffuse map
image = SOIL_load_image("container2.png", &width, &height, 0, SOIL_LOAD_RGB);
glBindTexture(GL_TEXTURE_2D, diffuseMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
glGenerateMipmap(GL_TEXTURE_2D);
SOIL_free_image_data(image);
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_NEAREST_MIPMAP_NEAREST);
// Specular map
image = SOIL_load_image("container2_specular.png", &width, &height, 0, SOIL_LOAD_RGB);
glBindTexture(GL_TEXTURE_2D, specularMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
glGenerateMipmap(GL_TEXTURE_2D);
SOIL_free_image_data(image);
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_NEAREST_MIPMAP_NEAREST);

image = SOIL_load_image("matrix.jpg", &width, &height, 0, SOIL_LOAD_RGB);
glBindTexture(GL_TEXTURE_2D, emissionMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
glGenerateMipmap(GL_TEXTURE_2D);
SOIL_free_image_data(image);
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_NEAREST_MIPMAP_NEAREST);

glBindTexture(GL_TEXTURE_2D, 0);

lightingShader.Use();
glUniform1i(glGetUniformLocation(lightingShader.Program, "material.diffuse"), 0);
glUniform1i(glGetUniformLocation(lightingShader.Program, "material.specular"), 1);
glUniform1i(glGetUniformLocation(lightingShader.Program, "material.emission"), 2);

// Game loop
while (!glfwWindowShouldClose(window))
{
// Calculate deltatime of current frame
GLfloat currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;

// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
glfwPollEvents();
do_movement();

// Clear the colorbuffer
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Use cooresponding shader when setting uniforms/drawing objects
lightingShader.Use();
GLint lightPosLoc = glGetUniformLocation(lightingShader.Program, "light.position");
GLint viewPosLoc = glGetUniformLocation(lightingShader.Program, "viewPos");
glUniform3f(lightPosLoc, lightPos.x, lightPos.y, lightPos.z);
glUniform3f(viewPosLoc, camera.Position.x, camera.Position.y, camera.Position.z);
// Set lights properties
glUniform3f(glGetUniformLocation(lightingShader.Program, "light.ambient"), 0.2f, 0.2f, 0.2f);
glUniform3f(glGetUniformLocation(lightingShader.Program, "light.diffuse"), 0.5f, 0.5f, 0.5f);
glUniform3f(glGetUniformLocation(lightingShader.Program, "light.specular"), 1.0f, 1.0f, 1.0f);
// Set material properties
glUniform1f(glGetUniformLocation(lightingShader.Program, "material.shininess"), 32.0f);

// Create camera transformations
glm::mat4 view;
view = camera.GetViewMatrix();
glm::mat4 projection = glm::perspective(camera.Zoom, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
// Get the uniform locations
GLint modelLoc = glGetUniformLocation(lightingShader.Program, "model");
GLint viewLoc = glGetUniformLocation(lightingShader.Program, "view");
GLint projLoc = glGetUniformLocation(lightingShader.Program, "projection");
// Pass the matrices to the shader
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

// Bind diffuse map
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, diffuseMap);
// Bind specular map
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, specularMap);

glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, emissionMap);

// Draw the container (using container's vertex attributes)
glBindVertexArray(containerVAO);
glm::mat4 model;
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);

// Also draw the lamp object, again binding the appropriate shader
lampShader.Use();
// Get location objects for the matrices on the lamp shader (these could be different on a different shader)
modelLoc = glGetUniformLocation(lampShader.Program, "model");
viewLoc = glGetUniformLocation(lampShader.Program, "view");
projLoc = glGetUniformLocation(lampShader.Program, "projection");
// Set matrices
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
model = glm::mat4();
model = glm::translate(model, lightPos);
model = glm::scale(model, glm::vec3(0.2f)); // Make it a smaller cube
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
// Draw the light object (using light's vertex attributes)
glBindVertexArray(lightVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
glBindVertexArray(0);

// Swap the screen buffers
glfwSwapBuffers(window);
}

// Terminate GLFW, clearing any resources allocated by GLFW.
glfwTerminate();
return 0;
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
if (key >= 0 && key < 1024)
{
if (action == GLFW_PRESS)
keys[key] = true;
else if (action == GLFW_RELEASE)
keys[key] = false;
}
}

void do_movement()
{
// Camera controls
if (keys[GLFW_KEY_W])
camera.ProcessKeyboard(FORWARD, deltaTime);
if (keys[GLFW_KEY_S])
camera.ProcessKeyboard(BACKWARD, deltaTime);
if (keys[GLFW_KEY_A])
camera.ProcessKeyboard(LEFT, deltaTime);
if (keys[GLFW_KEY_D])
camera.ProcessKeyboard(RIGHT, deltaTime);
}

bool firstMouse = true;
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
if (firstMouse)
{
lastX = xpos;
lastY = ypos;
firstMouse = false;
}

GLfloat xoffset = xpos - lastX;
GLfloat yoffset = lastY - ypos; // Reversed since y-coordinates go from bottom to left

lastX = xpos;
lastY = ypos;

camera.ProcessMouseMovement(xoffset, yoffset);
}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
camera.ProcessMouseScroll(yoffset);
}



Lighting.vs：
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 texCoords;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

out vec3 FragPos;
out vec3 Normal;
out vec2 TexCoords;

void main()
{
gl_Position = projection * view * model * vec4(position, 1.0f);
FragPos = vec3(model * vec4(position, 1.0f));
Normal = mat3(transpose(inverse(model))) * normal;
TexCoords = texCoords;
}

Lighting.frag:

#version 330 core
struct Material {
sampler2D diffuse;
sampler2D specular;
sampler2D emission;
float shininess;
};

struct Light {
vec3 position;

vec3 ambient;
vec3 diffuse;
vec3 specular;
};

in vec3 FragPos;
in vec3 Normal;
in vec2 TexCoords;

out vec4 color;

uniform vec3 viewPos;
uniform Material material;
uniform Light light;
uniform float time;

void main()
{
// Ambient
vec3 ambient = light.ambient * vec3(texture(material.diffuse, TexCoords));

// Diffuse
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(light.position - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = light.diffuse * diff * vec3(texture(material.diffuse, TexCoords));

// Specular
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
vec3 specular = light.specular * spec * vec3(texture(material.specular, TexCoords));

// Emission
vec3 emission = vec3(texture(material.emission, TexCoords));

color = vec4(ambient + diffuse + specular + emission, 1.0f);
}

Lamp.vs:
#version 330 core

layout (location = 0) in vec3 position;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
gl_Position = projection * view * model * vec4(position, 1.0f);
}

Lamp.frag:
#version 330 core
out vec4 color;

void main()
{
color = vec4(1.0f);
}