This article is a personal record of learning, learning is recommended to see the tutorial https://learnopengl-cn.github.io/
very grateful to the original author JoeyDeVries and quality tutorials, mostly Chinese translation provided by
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Foreword
In the real world, each object will have different light generating reaction, usually steel look more shiny than the ceramic vase, wooden box that is not as strong reflections of light steel box
Each object of the specular highlights also have different reactions, when some of the light reflected from the object will not have too much scattering (The Scatter), thus producing a smaller highlight dots, while others will be scattered many objects generated with a larger high spot radius, if we want to simulate various types of objects in OpenGL, we must define each object as a material (material) properties
Before we specify a color of an object and the light intensity of the specular light component and a combination of environmental, define visual output object, when describing an object, we can use these three components to define a color material (Material Color): ambient light (ambient lighting), diffuse lighting (diffuse lighting) and specular light (specular lighting). By specifying a color for each component, we can have a finer control of the color output of the object
Now, we add shininess (Shininess) the three color components to above, which has all the properties of the material we need the
//片段着色器
#version 330 core
struct Material {
vec3 ambient;
vec3 diffuse;
vec3 specular;
float shininess;
};
uniform Material material;
//......In the fragment shader, we create a structure (StructEntryTable) to store the material properties of the object, and simply declare a uniform variable
As you can see, we define a color for the vector components of each Feng illumination model , ambient material vector defined under ambient light reflected from an object that was what color, which is usually the same color and object color. Vector material diffuse color of the object is defined in diffuse lighting. (And as ambient illumination) diffuse color of the object we should set the desired color. vector specular material is disposed on the color impact specular lighting object (or possibly even a reflecting object specific color specular highlights). Finally, shininess specular highlights influence of scattering / radius.
These four elements define a material object, through which we can simulate a lot of real-world materials, devernay.free.fr a table on the show several material properties that simulate the real world of real material
It can be seen by specifying the material properties of an object correctly, our perception of the object is different, the effect is very obvious, of course, in order to get a more realistic effect, we ultimately need to be more complex shapes, not just a cube
Given a suitable material for an object it is very difficult, it requires a lot of experience and experiments, so due to improper material ruined the visual quality of the object is a thing often happens
We begin now to implement such a system in the material shader
Setting Material
We created the fragment shader in a uniform material structure, so let's hope that modify lighting calculations to adjust to the new material properties, since all the material variables are stored in the structure, we can access from uniform variable material in they:
//片段着色器
void main()
{
// 环境光
vec3 ambient = lightColor * material.ambient;
// 漫反射
vec3 norm = normalize(Normal);
vec3 lightDir = normalize(lightPos - FragPos);
float diff = max(dot(norm, lightDir), 0.0);
vec3 diffuse = lightColor * (diff * material.diffuse);
// 镜面光
vec3 viewDir = normalize(viewPos - FragPos);
vec3 reflectDir = reflect(-lightDir, norm);
float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
vec3 specular = lightColor * (spec * material.specular);
vec3 result = ambient + diffuse + specular;
FragColor = vec4(result, 1.0);
}We can see that we are now where needed access to all the properties of the material structure, and this is used to calculate the final output color based on the color of the material, the material properties of each object are multiplied by their corresponding light components
We can now set the program in the appropriate uniform, set the material of the object, the structure of GLSL when setting uniform and nothing special, just the structure as a uniform package variable, so if you want to fill this structure , we still need to be set for each individual uniform, but this time to bring the prefix name of the structure:
lightingShader.setVec3("material.ambient", 1.0f, 0.5f, 0.31f);
lightingShader.setVec3("material.diffuse", 1.0f, 0.5f, 0.31f);
lightingShader.setVec3("material.specular", 0.5f, 0.5f, 0.5f);
lightingShader.setFloat("material.shininess", 32.0f);我们将环境光和漫反射分量设置成我们想要让物体所拥有的颜色，而将镜面分量设置为一个中等亮度的颜色，我们不希望镜面分量在这个物体上过于强烈，我们将反光度保持为32，现在我们能够程序中非常容易地修改物体的材质了
但是又有一个问题，这个物体太亮了
光的属性
物体过亮的原因是环境光、漫反射和镜面光这三个颜色对任何一个光源都会去全力反射，光源对环境光、漫反射和镜面光分量也具有着不同的强度，之前我们通过使用一个强度值改变环境光和镜面光强度的方式解决了这个问题，我们想做一个类似的系统，但是这次是要为每个光照分量都指定一个强度向量
如果我们假设lightColor是vec3(1.0)，代码会看起来像这样：
vec3 ambient = vec3(1.0) * material.ambient;
vec3 diffuse = vec3(1.0) * (diff * material.diffuse);
vec3 specular = vec3(1.0) * (spec * material.specular);所以物体的每个材质属性对每一个光照分量都返回了最大的强度，对单个光源来说，这些vec3(1.0)值同样可以分别改变，而这通常就是我们想要的
现在，物体的环境光分量完全地影响了立方体的颜色，可是环境光分量实际上不应该对最终的颜色有这么大的影响，所以我们会将光源的环境光强度设置为一个小一点的值，从而限制环境光颜色：
vec3 ambient = vec3(0.1) * material.ambient;我们可以用同样的方式修改光源的漫反射和镜面光强度，这和我们之前做的极为相似，你可以说我们已经创建了一些光照属性来影响每个单独的光照分量，我们希望为光照属性创建一个与材质结构体类似的结构体：
struct Light {
vec3 position;
vec3 ambient;
vec3 diffuse;
vec3 specular;
};
uniform Light light;一个光源对它的ambient、diffuse和specular光照有着不同的强度。环境光照通常会设置为一个比较低的强度，因为我们不希望环境光颜色太过显眼。光源的漫反射分量通常设置为光所具有的颜色，通常是一个比较明亮的白色。镜面光分量通常会保持为vec3(1.0)，以最大强度发光。注意我们也将光源的位置添加到了结构体中。
和材质uniform一样，我们需要更新片段着色器：
vec3 ambient = light.ambient * material.ambient;
vec3 diffuse = light.diffuse * (diff * material.diffuse);
vec3 specular = light.specular * (spec * material.specular);我们接下来在程序中设置光照强度：
lightingShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);
lightingShader.setVec3("light.diffuse", 0.5f, 0.5f, 0.5f); // 将光照调暗了一些以搭配场景
lightingShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f); 现在我们调整了光照对物体材质的影响，我们应该能得到一个更类似于上一节的视觉效果。但这次我们有了对光照和物体材质的完全掌控：
不同的光源颜色
到目前为止，我们都只对光源设置了从白到灰到黑范围内的颜色，这样只会改变物体各个分量的强度，而不是它的真正颜色，由于现在能够非常容易地访问光照的属性了，我们可以随着时间改变它们的颜色，从而获得一些非常有意思的效果
由于所有的东西都在片段着色器中配置好了，修改光源的颜色非常简单
我们可以利用sin和glfwGetTime函数改变光源的环境光和漫反射颜色，从而很容易地让光源的颜色随着时间变化：
glm::vec3 lightColor;
lightColor.x = sin(glfwGetTime() * 2.0f);
lightColor.y = sin(glfwGetTime() * 0.7f);
lightColor.z = sin(glfwGetTime() * 1.3f);
glm::vec3 diffuseColor = lightColor * glm::vec3(0.5f); // 降低影响
glm::vec3 ambientColor = diffuseColor * glm::vec3(0.2f); // 很低的影响
lightingShader.setVec3("light.ambient", ambientColor);
lightingShader.setVec3("light.diffuse", diffuseColor);
源代码：
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "shader_s.h"
#include "camera.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>
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);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
// camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = SCR_WIDTH / 2.0f;
float lastY = SCR_HEIGHT / 2.0f;
bool firstMouse = true;
float deltaTime = 0.0f; // 当前帧与上一帧的时间差
float lastFrame = 0.0f; // 上一帧的时间
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);
int main()
{
// glfw初始化
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
// glfw创建窗口
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", 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);
// 捕捉鼠标
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
// glad加载所有OpenGL函数指针
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
glEnable(GL_DEPTH_TEST);
Shader lightingShader("colorVertex.txt", "colorFragment.txt");// 起什么名字自己定
Shader lampShader("lampVertex.txt", "lampFragment.txt");
float vertices[] = {
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f
};
unsigned int VBO;
glGenBuffers(1, &VBO);
unsigned int cubeVAO;
glGenVertexArrays(1, &cubeVAO);
glBindVertexArray(cubeVAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
//法向量属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
unsigned int lightVAO;
glGenVertexArrays(1, &lightVAO);
glBindVertexArray(lightVAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 渲染循环
while (!glfwWindowShouldClose(window))
{
// 帧时间差
float currentFrame = glfwGetTime();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
// 输入
processInput(window);
// 渲染指令
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
lightingShader.use();
lightingShader.setVec3("objectColor", 1.0f, 0.5f, 0.31f);
lightingShader.setVec3("lightColor", 1.0f, 1.0f, 1.0f);
lightingShader.setVec3("lightPos", lightPos);
lightingShader.setVec3("viewPos", camera.Position);
lightingShader.setVec3("material.ambient", 1.0f, 0.5f, 0.31f);
lightingShader.setVec3("material.diffuse", 1.0f, 0.5f, 0.31f);
lightingShader.setVec3("material.specular", 0.5f, 0.5f, 0.5f);
lightingShader.setFloat("material.shininess", 32.0f);
//lightingShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);
//lightingShader.setVec3("light.diffuse", 0.7f, 0.7f, 0.7f); // 将光照调暗了一些以搭配场景
lightingShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);
glm::vec3 lightColor;
lightColor.x = sin(glfwGetTime() * 2.0f);
lightColor.y = sin(glfwGetTime() * 0.7f);
lightColor.z = sin(glfwGetTime() * 1.3f);
glm::vec3 diffuseColor = lightColor * glm::vec3(0.5f); // 降低影响
glm::vec3 ambientColor = diffuseColor * glm::vec3(0.2f); // 很低的影响
lightingShader.setVec3("light.ambient", ambientColor);
lightingShader.setVec3("light.diffuse", diffuseColor);
// 初始化变换矩阵
glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
glm::mat4 view = camera.GetViewMatrix();
lightingShader.setMat4("projection", projection);
lightingShader.setMat4("view", view);
glm::mat4 model = glm::mat4();
lightingShader.setMat4("model", model);
glBindVertexArray(cubeVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
model = glm::translate(model, lightPos);
model = glm::scale(model, glm::vec3(0.2f));
lampShader.use();
// 设置模型、视图和投影矩阵uniform
lampShader.setMat4("projection", projection);
lampShader.setMat4("view", view);
model = glm::mat4(1.0f);
model = glm::translate(model, lightPos);
model = glm::scale(model, glm::vec3(0.2f)); // 小点的立方体
lampShader.setMat4("model", model);
// 绘制灯立方体对象
glBindVertexArray(lightVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
// 交换缓冲并查询IO事件
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &cubeVAO);
glDeleteBuffers(1, &VBO);
glfwTerminate();
return 0;
}
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)//是否按下了返回键
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);
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
glViewport(0, 0, width, height);
}
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
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;
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);
}