LearnOpenGL 光照—基础光照—练习题
作者：互联网
文章目录
初始代码
o b j e c t s h a d e r : object\ shader: object shader:
#version 330 core
layout (location = 0) in vec3 aPos; // 位置变量的属性位置值为 0
layout (location = 1) in vec3 aNormal;
uniform mat4 model; //模型
uniform mat4 view; //观察
uniform mat4 projection; //投影
out vec3 Normal;
out vec3 FragPos;
void main()
{
// 注意乘法要从右向左读
gl_Position = projection * view * model * vec4(aPos, 1.0);
Normal = mat3(transpose(inverse(model))) * aNormal;
FragPos = vec3(model * vec4(aPos, 1.0));
}
#version 330 core
in vec3 Normal;
in vec3 FragPos;
out vec4 FragColor;
uniform vec3 objectColor;
uniform vec3 lightColor;
uniform vec3 lightPos;
uniform vec3 viewPos;
void main()
{
//环境光
float ambientStrength=0.1;
vec3 ambient=ambientStrength*lightColor;
//漫反射
vec3 norm=normalize(Normal);
vec3 lightDir=normalize(lightPos-FragPos);
float diff=max(dot(norm,lightDir),0.0);
vec3 diffuse=diff*lightColor;
//镜面反射
float specularStrength=0.5;
vec3 viewDir=normalize(viewPos-FragPos);
vec3 reflectDir=reflect(-lightDir,norm);
float spec=pow(max(dot(reflectDir,viewDir),0.0),32);
vec3 specular=specularStrength*spec*lightColor;
//最终结果
vec3 result=(ambient+diffuse+specular)*objectColor;
FragColor=vec4(result,1.0);
}
c p p : cpp: cpp:
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <iostream>
#include "shader.h"
#include "stb_image.h"
#include "camera.h"
using std::cout;
//窗口回调函数
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
//绘图视口 3D坐标到2D坐标的转换(映射)和这些参数(宽高)有关
glViewport(0, 0, width, height);
}
//键盘回调
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
//鼠标回调
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
//滚轮回调
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
//窗口初始大小
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
//物体着色器
const char* vShaderPath = "ShaderFiles/shader.vs";
const char* fShaderPath = "ShaderFiles/shader.fs";
//光源着色器
const char* lightvShaderPath = "ShaderFiles/shader.vs";
const char* lightfShaderPath = "ShaderFiles/light_shader.fs";
//混合颜色的插值
float mixValue = 0.2f;
//记录鼠标坐标
float lastX, lastY;
bool firstMouse = true;
//摄像机
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
//光源位置
glm::vec3 lightPos(1.2f, 1.0f, 2.0f);
int main()
{
//glfw初始化
glfwInit();
//告诉glfw我们所使用的opengl版本 此处为3.3
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//创建窗口
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
cout << "Failed to create GLFW window\n";
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
//设置窗口回调函数
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//键盘回调函数
glfwSetKeyCallback(window, key_callback);
//鼠标回调
glfwSetCursorPosCallback(window, mouse_callback);
//滚轮回调
glfwSetScrollCallback(window, scroll_callback);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
cout << "Failed to initialize GLAD\n";
return -1;
}
//开启深度测试
glEnable(GL_DEPTH_TEST);
//着色器对象
Shader shaderProgram = Shader(vShaderPath, fShaderPath);
Shader lightShaderProgram = Shader(lightvShaderPath, lightfShaderPath);
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
};
//顶点缓冲对象 VBO
//顶点数组对象 VAO
unsigned int VBO, VAO;
//渲染物体
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
//设置顶点属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
//光源
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);
//线框模式
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
//这些uniform不会更新 可以放到循环外面
shaderProgram.use();
shaderProgram.setVec3("objectColor", 1.0f, 0.5f, 0.31f);
shaderProgram.setVec3("lightColor", 1.0f, 1.0f, 1.0f);
shaderProgram.setVec3("lightPos", lightPos);
while (!glfwWindowShouldClose(window))
{
glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//矩阵运算
glm::mat4 lightModel(1.0f);
glm::mat4 view = camera.GetViewMatrix();
glm::mat4 projection = glm::perspective(glm::radians(camera.Fov), SCR_WIDTH * 1.0f / SCR_HEIGHT, 0.1f, 100.0f);
//激活着色器
shaderProgram.use();
shaderProgram.setVec3("viewPos", camera.Position);
shaderProgram.setMat4("model", lightModel);
shaderProgram.setMat4("view", view);
shaderProgram.setMat4("projection", projection);
glBindVertexArray(VAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
//光源着色器
lightShaderProgram.use();
lightModel = glm::translate(lightModel, lightPos);
lightModel = glm::scale(lightModel, glm::vec3(0.2f));
lightShaderProgram.setMat4("model", lightModel);
lightShaderProgram.setMat4("view", view);
lightShaderProgram.setMat4("projection", projection);
glBindVertexArray(lightVAO);
glDrawArrays(GL_TRIANGLES, 0, 36);
glfwSwapBuffers(window);
glfwPollEvents();
}
//这一步是可选的
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
//glDeleteBuffers(1, &EBO);
//释放资源
glfwTerminate();
return 0;
}
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
if (action == GLFW_REPEAT || action == GLFW_PRESS)
{
if (key == GLFW_KEY_ESCAPE)
{
glfwSetWindowShouldClose(window, GL_TRUE);
return;
}
switch (key)
{
case GLFW_KEY_UP:
mixValue += 0.1f;
if (mixValue >= 1.0f)
mixValue = 1.0f;
break;
case GLFW_KEY_DOWN:
mixValue -= 0.1f;
if (mixValue <= 0.0f)
mixValue = 0.0f;
break;
case GLFW_KEY_W:
camera.ProcessKeyboard(FORWARD);
break;
case GLFW_KEY_S:
camera.ProcessKeyboard(BACKWARD);
break;
case GLFW_KEY_A:
camera.ProcessKeyboard(LEFT);
break;
case GLFW_KEY_D:
camera.ProcessKeyboard(RIGHT);
break;
default:
break;
}
}
}
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
if (firstMouse)
{
firstMouse = false;
lastX = xpos, lastY = ypos;
}
camera.ProcessMouseMovement(xpos - lastX, lastY - ypos);
lastX = xpos;
lastY = ypos;
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
camera.ProcessMouseScroll(yoffset);
}
练习一
目前，我们的光源是静止的，你可以尝试使用sin或cos函数让光源在场景中来回移动。观察光照随时间的改变能让你更容易理解冯氏光照模型。
思路：设当前时间为 t t t，自定义半径 r r r，得到 x = r ∗ c o s t , z = − r ∗ s i n t , y = r / 2 ∗ ( s i n t + c o s t ) x=r*cost,z=-r*sint,y=r/2*(sint+cost) x=r∗cost,z=−r∗sint,y=r/2∗(sint+cost)。
结果：
代码：在循环中增加以下语句，修改一下同名变量的位置即可：
float t = glfwGetTime(), r = 1.5f;
float sint = sinf(t), cost = cosf(t);
glm::vec3 lightPos(r * cost, -r * sint, r / 2 * (sint + cost));
练习二
尝试使用不同的环境光、漫反射和镜面强度，观察它们怎么是影响光照效果的。同样，尝试实验一下镜面光照的反光度因子。尝试理解为什么某一个值能够有着某一种视觉输出。
结果：设 K a 、 K d 、 K s K_a、K_d、K_s Ka、Kd、Ks分别代表环境光、漫反射、镜面反射的强度。
K
a
=
0.1
,
K
d
=
1.0
,
K
s
=
0.5
K_a=0.1,K_d=1.0,K_s=0.5
Ka=0.1,Kd=1.0,Ks=0.5
K
a
=
0.8
,
K
d
=
1.0
,
K
s
=
0.5
K_a=0.8,K_d=1.0,K_s=0.5
Ka=0.8,Kd=1.0,Ks=0.5
感觉
K
a
K_a
Ka增大，物体整体都会变量，和光源的位置无关。
K
a
=
0.1
,
K
d
=
2.0
,
K
s
=
0.5
K_a=0.1,K_d=2.0,K_s=0.5
Ka=0.1,Kd=2.0,Ks=0.5
感觉
K
d
K_d
Kd增大，法线和光源夹角<90°的部分会更亮，和光源位置有关。
K
a
=
0.1
,
K
d
=
1.0
,
K
s
=
1.0
K_a=0.1,K_d=1.0,K_s=1.0
Ka=0.1,Kd=1.0,Ks=1.0
感觉 K s K_s Ks增大，从反射视角看的部分会更亮，和光源位置、观察位置都有关。
强度不变，反光度因子由32增大到256：
明显看到高光点更加聚集。
练习三
在观察空间（而不是世界空间）中计算冯氏光照。
思路：修改着色器代码即可，注意传递给片段着色器的法向量、位置都要转换到观察坐标。而且光源位置也不能直接传递给uniform变量了(世界坐标系)，需要转换到观察坐标系。
o b j e c t s h a d e r : object\ shader: object shader:
#version 330 core
layout (location = 0) in vec3 aPos; // 位置变量的属性位置值为 0
layout (location = 1) in vec3 aNormal;
uniform mat4 model; //模型
uniform mat4 view; //观察
uniform mat4 projection; //投影
uniform vec3 lightPos;
out vec3 Normal;
out vec3 FragPos;
out vec3 LightPos;
void main()
{
// 注意乘法要从右向左读
gl_Position = projection * view * model * vec4(aPos, 1.0);
Normal = mat3(transpose(inverse(view*model))) * aNormal;
FragPos = vec3(view * model * vec4(aPos, 1.0));
LightPos = vec3(view * vec4(lightPos,1.0));
}
#version 330 core
in vec3 Normal;
in vec3 FragPos;
in vec3 LightPos;
out vec4 FragColor;
uniform vec3 objectColor;
uniform vec3 lightColor;
void main()
{
//观察空间下
vec3 viewPos=vec3(0.0,0.0,0.0);
//环境光
float ambientStrength=0.1;
vec3 ambient=ambientStrength*lightColor;
//漫反射
float diffuseStrength=1.0;
vec3 norm=normalize(Normal);
vec3 lightDir=normalize(LightPos-FragPos);
float diff=max(dot(norm,lightDir),0.0);
vec3 diffuse=diffuseStrength*diff*lightColor;
//镜面反射
float specularStrength=0.5;
vec3 viewDir=normalize(viewPos-FragPos);
vec3 reflectDir=reflect(-lightDir,norm);
float spec=pow(max(dot(reflectDir,viewDir),0.0),32);
vec3 specular=specularStrength*spec*lightColor;
//最终结果
vec3 result=(ambient+diffuse+specular)*objectColor;
FragColor=vec4(result,1.0);
}
练习四
尝试实现一个Gouraud着色（而不是冯氏着色）。如果你做对了话，立方体的光照应该会看起来有些奇怪，尝试推理为什么它会看起来这么奇怪。
能较为明显地看到条纹(两个三角形中间的那条线)。
o b j e c t s h a d e r : object\ shader: object shader:
#version 330 core
layout (location = 0) in vec3 aPos; // 位置变量的属性位置值为 0
layout (location = 1) in vec3 aNormal;
uniform mat4 model; //模型
uniform mat4 view; //观察
uniform mat4 projection; //投影
uniform vec3 lightPos;
uniform vec3 objectColor;
uniform vec3 lightColor;
out vec4 fragColor;
void main()
{
// 注意乘法要从右向左读
gl_Position = projection * view * model * vec4(aPos, 1.0);
vec3 Normal = mat3(transpose(inverse(view*model))) * aNormal;
vec3 FragPos = vec3(view * model * vec4(aPos, 1.0));
vec3 LightPos = vec3(view * vec4(lightPos,1.0));
//观察空间下
vec3 viewPos=vec3(0.0,0.0,0.0);
//环境光
float ambientStrength=0.1;
vec3 ambient=ambientStrength*lightColor;
//漫反射
float diffuseStrength=1.0;
vec3 norm=normalize(Normal);
vec3 lightDir=normalize(LightPos-FragPos);
float diff=max(dot(norm,lightDir),0.0);
vec3 diffuse=diffuseStrength*diff*lightColor;
//镜面反射
float specularStrength=0.5;
vec3 viewDir=normalize(viewPos-FragPos);
vec3 reflectDir=reflect(-lightDir,norm);
float spec=pow(max(dot(reflectDir,viewDir),0.0),32);
vec3 specular=specularStrength*spec*lightColor;
//最终结果
vec3 result=(ambient+diffuse+specular)*objectColor;
fragColor=vec4(result,1.0);
}
#version 330 core
in vec4 fragColor;
out vec4 FragColor;
void main()
{
FragColor=fragColor;
}
标签：练习题,1.0,0.0,float,0.5,uniform,LearnOpenGL,vec3,光照 来源： https://blog.csdn.net/xiji333/article/details/115052838