3.4 光照贴图

其他 2021-03-02 07:42:03 阅读次数: 0

光照贴图

引入漫反射和镜面光贴图(Map)，允许我们对物体的漫反射分量）和镜面光分量有着更精确的控制。

漫反射贴图

漫反射贴图相当于纹理，实际上这两者都已一张覆盖物体的图像，让我们能够逐片段索引其独立的颜色值。

镜面光贴图

通过使用镜面光贴图我们可以可以对物体设置大量的细节，比如物体的哪些部分需要有闪闪发光的属性，我们甚至可以设置它们对应的强度。镜面光贴图能够在漫反射贴图之上给予我们更高一层的控制。

code

漫反射贴图+镜面光贴图

#include "../env/glm/glm.hpp"
#include "../env/glm/gtc/matrix_transform.hpp"
#include "../env/glm/gtc/type_ptr.hpp"
#include <iostream>

#define STB_IMAGE_IMPLEMENTATION
#include "../env/std_image.h"
#include "../env/glad.h"
#include "../env/glfw3.h"
#include <fstream>
#include "../tools/shader.h"
#include "../tools/camera.h"

#define WIDTH 800
#define HEIGHT 600

GLFWwindow *initialize(int width, int height);

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);

Camera camera = Camera(glm::vec3(0.0f, 0.0f, 3.0f),
                       glm::vec3(0.0f, 0.0f, -1.0f),
                       glm::vec3(0.0f, 1.0f, 0.0f),
                       0.0f, 0.0f);

float cameraSpeed = 2.5f;
float lastTime;
float lastXPos;
float lastYPos;
bool firstMouse;
float fov = 45.0f;

int main()
{
    
    
    GLFWwindow *window = initialize(WIDTH, HEIGHT);
    float 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};

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

    GLuint objectVAO;
    glGenVertexArrays(1, &objectVAO);
    glBindVertexArray(objectVAO);
    glBindBuffer(GL_ARRAY_BUFFER, myVBO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(3 * sizeof(float)));
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(6 * sizeof(float)));

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);
    glEnableVertexAttribArray(2);

    GLuint lightVAO;
    glGenVertexArrays(1, &lightVAO);
    glBindVertexArray(lightVAO);
    glBindBuffer(GL_ARRAY_BUFFER, myVBO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

    int width, height, channel;
    unsigned char *data = stbi_load("../images/container2.png", &width, &height, &channel, 0);

    std::cout << width << " " << height << " " << channel << std::endl;

    GLuint diffuseTexture;
    glGenTextures(1, &diffuseTexture);
    glBindTexture(GL_TEXTURE_2D, diffuseTexture);

    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);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);

    stbi_image_free(data);

    data = stbi_load("../images/container2_specular.png", &width, &height, &channel, 0);
    std::cout << width << " " << height << " " << channel << std::endl;

    GLuint specularTexture;
    glGenTextures(1, &specularTexture);
    glBindTexture(GL_TEXTURE_2D, specularTexture);

    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);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);

    glm::mat4 model, view, projection;
    Shader lampShader("1-vertex.glsl", "1-lamp-fragment.glsl");
    Shader lightShader("4-vertex.glsl", "4-fragment.glsl");

    lastTime = glfwGetTime();
    glEnable(GL_DEPTH_TEST);

    while (!glfwWindowShouldClose(window))
    {
    
    
        model = glm::mat4(1.0f);
        glm::vec3 lightPos = glm::vec3(1.2f, 1.0f, 2.0f);
        model = glm::translate(model, lightPos);
        model = glm::scale(model, glm::vec3(0.2f));

        view = camera.lookAt();
        projection = glm::perspective(glm::radians(fov), 1.0f * WIDTH / HEIGHT, 0.1f, 100.0f);

        lampShader.use();
        lampShader.setm4fv("model", GL_FALSE, glm::value_ptr(model));
        lampShader.setm4fv("view", GL_FALSE, glm::value_ptr(view));
        lampShader.setm4fv("projection", GL_FALSE, glm::value_ptr(projection));
        glBindVertexArray(lightVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        model = glm::mat4(1.0f);
        lightShader.use();
        lightShader.setm4fv("model", GL_FALSE, glm::value_ptr(model));
        lightShader.setm4fv("view", GL_FALSE, glm::value_ptr(view));
        lightShader.setm4fv("projection", GL_FALSE, glm::value_ptr(projection));

        glm::vec3 lightColor = glm::vec3(1.0f, 1.0f, 1.0f);
        lightShader.setv3("lightColor", glm::value_ptr(lightColor));

        glm::vec3 cameraPos = camera.getPosition();
        lightShader.setv3("viewPos", glm::value_ptr(cameraPos));
        lightShader.setv3("lightPos", glm::value_ptr(lightPos));

        glm::vec3 ambient = glm::vec3(1.0f, 0.5f, 0.31f);
        glm::vec3 diffuse = glm::vec3(1.0f, 0.5f, 0.31f);
        glm::vec3 specular = glm::vec3(0.5f, 0.5f, 0.5f);
  
        float shiness = 64.0f;
        lightShader.setf("material.shiness", shiness);

        ambient = glm::vec3(0.2f, 0.2f, 0.2f);
        diffuse = glm::vec3(0.5f, 0.5f, 0.5f);
        specular = glm::vec3(1.0f, 1.0f, 1.0f);

        lightShader.setv3("light.ambient", glm::value_ptr(ambient));
        lightShader.setv3("light.diffuse", glm::value_ptr(diffuse));
        lightShader.setv3("light.specular", glm::value_ptr(specular));

        lightShader.seti("material.diffuse", 0);
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, diffuseTexture);

        lightShader.seti("material.specular", 1);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, specularTexture);
        
        glBindVertexArray(objectVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        processInput(window);
        glfwSwapBuffers(window);
        glfwPollEvents();
        glClearColor(0.0, 0.0, 0.0, 0.0);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    }

    glfwTerminate();
    return 0;
}

void framebuffer_size_callback(GLFWwindow *window, int width, int height)
{
    
    
    glViewport(0, 0, width, height);
}

void processInput(GLFWwindow *window)
{
    
    
    float currentTime = glfwGetTime();
    float delta = currentTime - lastTime;
    lastTime = currentTime;
    float distance = cameraSpeed * delta;

    // 移动照相机位置
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
    {
    
    
        glfwSetWindowShouldClose(window, true);
    }
    else if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::FORWARD, distance);
    }
    else if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::BACKWARD, distance);
    }
    else if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::LEFT, distance);
    }
    else if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::RIGHT, distance);
    }
    else if (glfwGetKey(window, GLFW_KEY_E) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::DOWN, distance);
    }
    else if (glfwGetKey(window, GLFW_KEY_Q) == GLFW_PRESS)
    {
    
    
        camera.move(CameraMovement::UP, distance);
    }
}

GLFWwindow *initialize(int width, int height)
{
    
    
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    GLFWwindow *window = glfwCreateWindow(WIDTH, HEIGHT, "2", nullptr, nullptr);
    if (!window)
    {
    
    
        exit(-1);
    }

    glfwMakeContextCurrent(window);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
    
    
        exit(-1);
    }

    glViewport(0, 0, width, height);

    glfwSetWindowSizeCallback(window, framebuffer_size_callback);

    // 光标初始位置
    lastXPos = 400;
    lastYPos = 300;
    firstMouse = true;
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
    glfwSetCursorPosCallback(window, mouse_callback);

    glfwSetScrollCallback(window, scroll_callback);

    return window;
}

void mouse_callback(GLFWwindow *window, double xpos, double ypos)
{
    
    
    if (firstMouse)
    {
    
    
        lastXPos = xpos;
        lastYPos = ypos;
        firstMouse = false;
    }

    float sensitivity = 0.05f;
    float xOffset = (xpos - lastXPos) * sensitivity;
    float yOffset = (lastYPos - ypos) * sensitivity;

    lastXPos = xpos;
    lastYPos = ypos;

    camera.rotate(xOffset, yOffset);
}

void scroll_callback(GLFWwindow *window, double xoffset, double yoffset)
{
    
    
    fov -= yoffset;
    if (fov <= 1.0f)
    {
    
    
        fov = 1.0f;
    }
    if (fov >= 45.0f)
    {
    
    
        fov = 45.0f;
    }
}

4-vertex.glsl

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoord;

out vec3 Normal;
out vec3 fragPos;
out vec2 ourTexCoord;

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

void main() {
    gl_Position = projection * view * model * vec4(aPos, 1.0f);
    fragPos = vec3(model * vec4(aPos, 1.0f));
    // 物体变换到世界坐标时，法向量也应当跟随着变换过去
    Normal = mat3(transpose(inverse(model))) * aNormal;
    ourTexCoord = aTexCoord;
}

4-fragment.glsl

#version 330 core

struct Material{
    sampler2D diffuse;
    sampler2D specular;
    float shiness;
};

struct Light{
    vec3 position, ambient, diffuse, specular;
};

in vec3 Normal;
in vec3 fragPos;
in vec2 ourTexCoord;

uniform vec3 lightColor;
uniform vec3 objectColor;
uniform vec3 lightPos;
uniform vec3 viewPos;
uniform Material material;
uniform Light light;

out vec4 FragColor;

void main() {
    vec3 ambientStrength = vec3(texture(material.diffuse, ourTexCoord)) * light.ambient;

    vec3 lightDir = normalize(lightPos - fragPos);
    vec3 normal = normalize(Normal);
    vec3 diffuseStrength = max(0.0f, dot(normal, lightDir)) * vec3(texture(material.diffuse, ourTexCoord)) * light.diffuse;
    
    vec3 viewDir = normalize(viewPos - fragPos);
    vec3 reflectDir = reflect(-lightDir, normal);
    vec3 specularStrength = pow(max(0.0f, dot(viewDir, reflectDir)), material.shiness) * vec3(texture(material.specular, ourTexCoord)) * light.specular;

    FragColor = vec4((ambientStrength + diffuseStrength + specularStrength)* lightColor, 1.0f);
}

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