OpenGL基础17：颜色加载中…-

一、RGB三原色

回想一下初中物理知识：

1. 三原色：自然界中所有的颜色都可以用红、绿、蓝(RGB)这三种颜色频率的不同强度组合而得，白色包含了所有颜色
2. 能看到一个物体的颜色，是这个物体(Reflected)反射的颜色，换句话说，就是不能被当前物体吸收(Absorb)的颜色
3. 之所以能看到五彩斑斓的世界，是因为存在光源（发光的物体），否则将是完全的黑暗
4. 结合②③，颜色从光源到我们的眼睛，大致就是这样一个过程：光源发出光线 → 照射到物体上 → 物体反射所有光源中存在，但不能被其吸收的颜色

计算机如何表示颜色（应该算是个很基础的东西了）：

1. RGBA：RGB代表3原色，一般在(0, 255)的范围内，越大对应颜色越深，A代表透明度，可以转换成对应浮点数，例如0.5就等于128（HEX格式：#FFB6C1FF  →  对应RGBA格式：255,182,193, 255）
2. 由①可见，计算机能表现的颜色数量其实是有限的，总共（256 * 256 * 256）种不同颜色，这也是所谓的 8-bit 采样，现在部分支持 10 – bit 采样，在这种情况下能表现出总共 (1024 * 1024 * 1024) 种不同颜色

二、光照场景

回想 OpenGL基础5：第一个正方形 这一章

在这一章的时候，还没有接触到纹理，在颜色方面，也只是随便给他赋了个颜色

在此之后用了纹理，也就是简简单单的把颜色这一属性去掉了

现在重新考虑颜色这一属性，不再简单给物体随便赋颜色了，而是直接开始模拟光照！以给与物体一个真实的“颜色”，在此之前，先用前面的知识生成一个这样的场景：

其中白色的正方体是光源，珊瑚红色的正方体是物体

白色光源的着色器代码如下（LightFShader.txt 和 LightVShader）：

 #version 330 core out vec4 color; void main() {     color = vec4(1.0f); }  /////////////////////////////////////////////////////  #version 330 core layout (location = 0) in vec3 position; uniform mat4 model;             //模型矩阵 uniform mat4 view;              //观察矩阵 uniform mat4 projection;        //投影矩阵 void main() {     gl_Position = projection * view * model * vec4(position, 1.0); }

珊瑚红物体的着色器如下（ObjFShader.txt 和 ObjVShader）：

 #version 330 core out vec4 color; uniform vec3 objectColor; uniform vec3 lightColor; in vec2 texIn; uniform sampler2D texOutA; void main() {     color = vec4(lightColor * objectColor, 1.0f); }  /////////////////////////////////////////////////////  #version 330 core layout (location = 0) in vec3 position; layout (location = 1) in vec2 texture; out vec2 texIn; uniform mat4 model;             //模型矩阵 uniform mat4 view;              //观察矩阵 uniform mat4 projection;        //投影矩阵 void main() {     gl_Position = projection * view * model * vec4(position, 1.0);     //texIn = vec2(texture.x, 1.0f - texture.y);   //暂时屏蔽纹理 }

对于物体的顶点着色器，我们定义了两个uniform变量，分别代表着物体颜色和光照颜色

当我们把光源的颜色与物体的颜色相乘，所得到的就是这个物体所反射该光源的颜色(也就是我们感知到的颜色)

接下来就是主代码（Camera.h 和 Shader.h未改变，可以从前面的章节中找到）：

 #include<iostream> #include<opengl/glew.h> #define GLEW_STATIC #include<GLFW/glfw3.h> #include"Camera.h" #include<glm/glm.hpp> #include<glm/gtc/matrix_transform.hpp> #include<glm/gtc/type_ptr.hpp> #include"Shader.h" #include<opengl/freeglut.h> #include<SOIL.h>  bool keys[1024]; Camera camera; GLfloat lastX, lastY; bool firstMouse = true; void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode); void scroll_callback(GLFWwindow* window, double xoffset, double yoffset); void mouse_callback(GLFWwindow* window, double xpos, double ypos); void cameraMove(); glm::vec3 lightPos(1.2f, 1.0f, 2.0f); const GLuint WIDTH = 800, HEIGHT = 600;  int main() {     glfwInit();     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);      GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);     glfwMakeContextCurrent(window);     glfwSetKeyCallback(window, key_callback);     glfwSetCursorPosCallback(window, mouse_callback);     glfwSetScrollCallback(window, scroll_callback);      glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);     glewExperimental = GL_TRUE;     glewInit();      int width, height;     glfwGetFramebufferSize(window, &width, &height);     glViewport(0, 0, width, height);      Shader shaderObj("ObjVShader.txt", "ObjFShader.txt");     Shader shaderLight("LightVShader.txt", "LightFShader.txt");      GLfloat vertices[] =      {         -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,          0.5f, -0.5f, -0.5f,  1.0f, 0.0f,          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,         -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,         -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,          -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,          0.5f, -0.5f,  0.5f,  1.0f, 0.0f,          0.5f,  0.5f,  0.5f,  1.0f, 1.0f,          0.5f,  0.5f,  0.5f,  1.0f, 1.0f,         -0.5f,  0.5f,  0.5f,  0.0f, 1.0f,         -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,          -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,         -0.5f,  0.5f, -0.5f,  1.0f, 1.0f,         -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,         -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,         -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,         -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,           0.5f,  0.5f,  0.5f,  1.0f, 0.0f,          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,          0.5f, -0.5f, -0.5f,  0.0f, 1.0f,          0.5f, -0.5f, -0.5f,  0.0f, 1.0f,          0.5f, -0.5f,  0.5f,  0.0f, 0.0f,          0.5f,  0.5f,  0.5f,  1.0f, 0.0f,          -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,          0.5f, -0.5f, -0.5f,  1.0f, 1.0f,          0.5f, -0.5f,  0.5f,  1.0f, 0.0f,          0.5f, -0.5f,  0.5f,  1.0f, 0.0f,         -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,         -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,          -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,          0.5f,  0.5f, -0.5f,  1.0f, 1.0f,          0.5f,  0.5f,  0.5f,  1.0f, 0.0f,          0.5f,  0.5f,  0.5f,  1.0f, 0.0f,         -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,         -0.5f,  0.5f, -0.5f,  0.0f, 1.0f     };     GLuint VBO, VAO, texture;     glGenVertexArrays(1, &VAO);     glGenBuffers(1, &VBO);     glGenTextures(1, &texture);      glBindVertexArray(VAO);     glBindBuffer(GL_ARRAY_BUFFER, VBO);     glBindTexture(GL_TEXTURE_2D, texture);      glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);     glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);     glEnableVertexAttribArray(0);     /*glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));     glEnableVertexAttribArray(1);      int picWidth, picHeight;     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);     unsigned char* image = SOIL_load_image("Texture/wood.jpg", &picWidth, &picHeight, 0, SOIL_LOAD_RGB);     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, picWidth, picHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, image);     glGenerateMipmap(GL_TEXTURE_2D);     SOIL_free_image_data(image);     glBindTexture(GL_TEXTURE_2D, 0);*/      GLuint lightVAO;     glGenVertexArrays(1, &lightVAO);     glBindVertexArray(lightVAO);     glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);     //VBO数据已经绑定且我们就用之前的顶点数据，所以无需再管理VBO     glEnableVertexAttribArray(0);      glBindBuffer(GL_ARRAY_BUFFER, 0);     glBindVertexArray(0);      glEnable(GL_DEPTH_TEST);     while (!glfwWindowShouldClose(window))     {         glfwPollEvents();         glClearColor(0.2f, 0.3f, 0.3f, 1.0f);         glClear(GL_COLOR_BUFFER_BIT);         glClear(GL_DEPTH_BUFFER_BIT);         cameraMove();          //glBindTexture(GL_TEXTURE_2D, texture);         shaderObj.Use();         GLint objectColorLoc = glGetUniformLocation(shaderObj.Program, "objectColor");         GLint lightColorLoc = glGetUniformLocation(shaderObj.Program, "lightColor");         glUniform3f(objectColorLoc, 1.0f, 0.5f, 0.31f);     //物体反射颜色         glUniform3f(lightColorLoc, 1.0f, 1.0f, 1.0f);       //光源：默认为白色         glm::mat4 model = glm::mat4(1.0f);         glm::mat4 view = glm::mat4(1.0f);         glm::mat4 projection = glm::mat4(1.0f);         model = glm::rotate(model, glm::radians(57.0f), glm::vec3(-0.5f, 1.0f, 0.0f));         view = camera.GetViewMatrix();         projection = glm::perspective(glm::radians(camera.Zoom), (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);         GLint modelLoc = glGetUniformLocation(shaderObj.Program, "model");         GLint viewLoc = glGetUniformLocation(shaderObj.Program, "view");         GLint projLoc = glGetUniformLocation(shaderObj.Program, "projection");         glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));         glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));         glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));          glBindVertexArray(VAO);         glDrawArrays(GL_TRIANGLES, 0, 36);          //glBindTexture(GL_TEXTURE_2D, 0);         shaderLight.Use();         model = glm::translate(glm::mat4(1.0f), lightPos);         model = glm::scale(model, glm::vec3(0.2f));         modelLoc = glGetUniformLocation(shaderLight.Program, "model");         viewLoc = glGetUniformLocation(shaderLight.Program, "view");         projLoc = glGetUniformLocation(shaderLight.Program, "projection");         glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));         glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));         glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));          glBindVertexArray(lightVAO);         glDrawArrays(GL_TRIANGLES, 0, 36);          glBindVertexArray(0);         glfwSwapBuffers(window);     }     glDeleteVertexArrays(1, &VAO);     glDeleteBuffers(1, &VBO);     glfwTerminate();     return 0; }   GLfloat deltaTime = 0.0f; GLfloat lastFrame = 0.0f; void cameraMove() {     GLfloat currentFrame = glfwGetTime();     deltaTime = currentFrame - lastFrame;     lastFrame = currentFrame;      GLfloat cameraSpeed = 1.0f * deltaTime;     if (keys[GLFW_KEY_W])         camera.ProcessKeyboard(Camera_Movement(FORWARD), deltaTime);     if (keys[GLFW_KEY_S])         camera.ProcessKeyboard(Camera_Movement(BACKWARD), deltaTime);     if (keys[GLFW_KEY_A])         camera.ProcessKeyboard(Camera_Movement(LEFT), deltaTime);     if (keys[GLFW_KEY_D])         camera.ProcessKeyboard(Camera_Movement(RIGHT), deltaTime); }  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 (action == GLFW_PRESS)           //如果当前是按下操作         keys[key] = true;     else if (action == GLFW_RELEASE)            //松开键盘         keys[key] = false; }  void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) {     camera.ProcessMouseScroll(yoffset); }  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;     lastX = xpos;     lastY = ypos;          GLfloat sensitivity = 0.05;     xoffset *= sensitivity;     yoffset *= sensitivity;          camera.ProcessMouseMovement(xoffset, yoffset); }