高級OpenGL之立方體貼圖——引入反射貼圖升級納米裝模型

模型加載主程序：

#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <fstream>
#include <sstream>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "Shader.h"
#include "Camera.h"
#include "Model.h"
#define _USE_MATH_DEFINES
#include<math.h>
void framebuffer_size_callback(GLFWwindow* windows, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void processInput(GLFWwindow *windows);
void scroll_callback(GLFWwindow *window, double xoffset, double yoffset);
unsigned int loadCubemap(vector<std::string> faces);

#define ambient_light 0.1 //定義四個點光源的環境光影響
#define specular_light 0.05	// 定義四個點光源鏡面反射的影響

#define screenWidth 800
#define screenHeight 600

Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
float lastX = screenWidth / 2.0f;
float lastY = screenHeight / 2.0f;
bool firstMouse = true;

//timing
float deltaTime = 0.2f;
float lastFrame = 0.0f;

glm::vec3 pointLightPositions[] = {
	glm::vec3(0.7f,  0.2f,  2.0f),
	glm::vec3(2.3f, -3.3f, -4.0f),
	glm::vec3(-4.0f,  2.0f, -12.0f),
	glm::vec3(0.0f,  0.0f, -3.0f)
};
vector<std::string>faces
{
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/right.jpg",
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/left.jpg",
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/top.jpg",
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/bottom.jpg",
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/back.jpg",
	"D:/opengltask/LearnOpenGL_master/resources/textures/skybox/front.jpg"
};
//立方體貼圖頂點座標數據
float skyboxVertices[] = {
	// positions          
	-1.0f,  1.0f, -1.0f,
	-1.0f, -1.0f, -1.0f,
	1.0f, -1.0f, -1.0f,
	1.0f, -1.0f, -1.0f,
	1.0f,  1.0f, -1.0f,
	-1.0f,  1.0f, -1.0f,

	-1.0f, -1.0f,  1.0f,
	-1.0f, -1.0f, -1.0f,
	-1.0f,  1.0f, -1.0f,
	-1.0f,  1.0f, -1.0f,
	-1.0f,  1.0f,  1.0f,
	-1.0f, -1.0f,  1.0f,

	1.0f, -1.0f, -1.0f,
	1.0f, -1.0f,  1.0f,
	1.0f,  1.0f,  1.0f,
	1.0f,  1.0f,  1.0f,
	1.0f,  1.0f, -1.0f,
	1.0f, -1.0f, -1.0f,

	-1.0f, -1.0f,  1.0f,
	-1.0f,  1.0f,  1.0f,
	1.0f,  1.0f,  1.0f,
	1.0f,  1.0f,  1.0f,
	1.0f, -1.0f,  1.0f,
	-1.0f, -1.0f,  1.0f,

	-1.0f,  1.0f, -1.0f,
	1.0f,  1.0f, -1.0f,
	1.0f,  1.0f,  1.0f,
	1.0f,  1.0f,  1.0f,
	-1.0f,  1.0f,  1.0f,
	-1.0f,  1.0f, -1.0f,

	-1.0f, -1.0f, -1.0f,
	-1.0f, -1.0f,  1.0f,
	1.0f, -1.0f, -1.0f,
	1.0f, -1.0f, -1.0f,
	-1.0f, -1.0f,  1.0f,
	1.0f, -1.0f,  1.0f
};
glm::mat4 model = glm::mat4(1.0f);
unsigned int cubemapVAO, cubemapVBO;
int main()
{
	//glfw:initialize and configure
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	GLFWwindow *window = glfwCreateWindow(screenWidth, screenHeight, "model_loading", 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);

	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	model = glm::translate(model, glm::vec3(0.0f, -1.75f, 0.0f));	//	使其處於場景的中心
	model = glm::scale(model, glm::vec3(0.2f, 0.2f, 0.2f));

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}
	glEnable(GL_DEPTH_TEST);
	unsigned int cubemapTexture = loadCubemap(faces);
	//對於立方體貼圖的VAO
	glGenVertexArrays(1, &cubemapVAO);
	glGenBuffers(1, &cubemapVBO);
	glBindVertexArray(cubemapVAO);
	glBindBuffer(GL_ARRAY_BUFFER, cubemapVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices), &skyboxVertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
	glBindVertexArray(0);


	Shader ourShader("1.model_loading.vs", "1.model_loading.fs");
	Shader skyboxShader = Shader("cubemap.vs", "cubemap.fs");	//天空盒對應頂點着色器和片段着色器
	Model ourModel("D:/opengltask/LearnOpenGL_master/resources/objects/nanosuit/nanosuit.obj");
	while (!glfwWindowShouldClose(window))
	{
		float currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;
		processInput(window);
		ourShader.setVec3("viewPos", camera.Position);
		glClearColor(0.05f, 0.05f, 0.05f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		ourShader.use();
		// point light 1
		ourShader.setVec3("pointLights[0].position", pointLightPositions[0]);
		ourShader.setVec3("pointLights[0].ambient", ambient_light, ambient_light, ambient_light);
		ourShader.setVec3("pointLights[0].diffuse", 1.0f, 1.0f, 1.0f);
		ourShader.setVec3("pointLights[0].specular", specular_light, specular_light, specular_light);
		ourShader.setFloat("pointLights[0].constant", 1.0f);
		ourShader.setFloat("pointLights[0].linear", 0.09);
		ourShader.setFloat("pointLights[0].quadratic", 0.032);
		// point light 2
		ourShader.setVec3("pointLights[1].position", pointLightPositions[1]);
		ourShader.setVec3("pointLights[1].ambient", ambient_light, ambient_light, ambient_light);
		ourShader.setVec3("pointLights[1].diffuse", 0.8f, 0.8f, 0.8f);
		ourShader.setVec3("pointLights[1].specular", specular_light, specular_light, specular_light);
		ourShader.setFloat("pointLights[1].constant", 1.0f);
		ourShader.setFloat("pointLights[1].linear", 0.09);
		ourShader.setFloat("pointLights[1].quadratic", 0.032);
		// point light 3
		ourShader.setVec3("pointLights[2].position", pointLightPositions[2]);
		ourShader.setVec3("pointLights[2].ambient", ambient_light, ambient_light, ambient_light);
		ourShader.setVec3("pointLights[2].diffuse", 0.8f, 0.8f, 0.8f);
		ourShader.setVec3("pointLights[2].specular", specular_light, specular_light, specular_light);
		ourShader.setFloat("pointLights[2].constant", 1.0f);
		ourShader.setFloat("pointLights[2].linear", 0.09);
		ourShader.setFloat("pointLights[2].quadratic", 0.032);
		// point light 4
		ourShader.setVec3("pointLights[3].position", pointLightPositions[3]);
		ourShader.setVec3("pointLights[3].ambient", ambient_light, ambient_light, ambient_light);
		ourShader.setVec3("pointLights[3].diffuse", 0.8f, 0.8f, 0.8f);
		ourShader.setVec3("pointLights[3].specular", specular_light, specular_light, specular_light);
		ourShader.setFloat("pointLights[3].constant", 1.0f);
		ourShader.setFloat("pointLights[3].linear", 0.09);
		ourShader.setFloat("pointLights[3].quadratic", 0.032);
		ourShader.setInt("material.skybox", 3);
		glActiveTexture(GL_TEXTURE3);
		glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);


		//ourShader.setVec3("material.specular", 0.5f, 0.5f, 0.5f);
		ourShader.setFloat("material.shininess", 128.0f);

		glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)screenWidth/ (float)screenHeight, 0.1f, 100.0f);
		glm::mat4 view = camera.GetViewMatrix();
		ourShader.setMat4("projection", projection);
		ourShader.setMat4("view", view);
		ourShader.setMat4("model", model);
		ourModel.Draw(ourShader);

		glBindVertexArray(0);
		glDepthFunc(GL_LEQUAL);	//深度緩衝將會填充上天空盒的1.0，所以需要保證天空盒在值小於或等於深度緩衝時通過深度測試
		skyboxShader.use();
		view = glm::mat4(glm::mat3(camera.GetViewMatrix()));		//取矩陣左上角得3*3矩陣來移除變換矩陣的位移部分
		skyboxShader.setMat4("view", view);
		skyboxShader.setMat4("projection", projection);
		glBindVertexArray(cubemapVAO);
		glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
		glDrawArrays(GL_TRIANGLES, 0, 36);
		glBindVertexArray(0);
		glDepthFunc(GL_LESS);


		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	glfwTerminate();
	return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)	//視口根據窗口大小調整的函數，兩個整數表示窗口的新維度
{
	glViewport(0, 0, width, height);
}
void processInput(GLFWwindow *window)	//輸入的控制
{
	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);

	if (glfwGetKey(window, GLFW_KEY_L) == GLFW_PRESS)
		model = glm::rotate(model, (float)(M_PI/ 360.0), glm::vec3(0.0f, 1.0f, 0.0f));
	if (glfwGetKey(window, GLFW_KEY_R) == GLFW_PRESS)
		model = glm::rotate(model, (float)(-M_PI / 360.0), glm::vec3(0.0f, 1.0f, 0.0f));
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)	//	glfwGetKey函數需要一個窗口以及一個按鍵作爲輸入，函數將會返回這個按鍵是否正在被按下
		glfwSetWindowShouldClose(window, true);
}
void mouse_callback(GLFWwindow* window, double xpos, double ypos)	//鼠標回調函數
{
	if (firstMouse)
	{
		lastX = xpos;
		lastY = ypos;
		firstMouse = false;
	}
	float xoffset = xpos - lastX;
	float yoffset = lastY - ypos;	//相反的，因爲y座標是從底部往頂部依次增大的
	lastX = xpos;
	lastY = ypos;
	camera.ProcessMouseMovement(xoffset, yoffset);
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)	//鼠標滾輪的回調函數
{
	camera.ProcessMouseScroll(yoffset);
}
unsigned int loadCubemap(vector<std::string> faces)	//創建立方體貼圖
{
	unsigned int textureID;
	glGenTextures(1, &textureID);
	glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);

	int width, height, nrChannels;
	for (unsigned int i = 0; i < faces.size(); i++)
	{
		unsigned char *data = stbi_load(faces[i].c_str(), &width, &height, &nrChannels, 0);
		if (data)
		{
			glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
			stbi_image_free(data);
		}
		else
		{
			std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
			stbi_image_free(data);
		}
	}
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);

	return textureID;
}

模型對應頂點着色器：

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

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

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
	TexCoords=aTexCoords;
	gl_Position=projection*view*model*vec4(aPos,1.0);
	FragPos=vec3(model*vec4(aPos,1.0));
	Normal=mat3(transpose(inverse(model)))*aNormal;
}

模型對應片段着色器：

#version 330 core
out vec4 FragColor;

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

uniform vec3 viewPos;
struct Material{
	sampler2D texture_diffuse1;
	sampler2D texture_specular1;
    sampler2D texture_ambient1;
    samplerCube skybox;
	float shininess;
};

struct PointLight{
      vec3 position;
      float constant;
      float linear;
      float quadratic;
      vec3 ambient;
      vec3 diffuse;
      vec3 specular;
};
vec3 CalcPointLight(PointLight light ,vec3 normal,vec3 fragPos,vec3 viewDir);
//uniform Light light;
#define NR_POINT_LIGHTS 4
uniform PointLight pointLights[NR_POINT_LIGHTS];
uniform Material material;
void main()
{
    vec3 norm=normalize(Normal);
    vec3 viewDir=normalize(viewPos-FragPos);
     vec3 R=reflect(-viewDir,norm); 
     vec3 result=vec3(0.0);
    for (int i=0;i<NR_POINT_LIGHTS;i++)
    {
        result+=CalcPointLight(pointLights[i],norm,FragPos,viewDir);
    }
    result+=texture(material.skybox,R).rgb*texture(material.texture_ambient1,TexCoords).rgb;
    FragColor=vec4(result,1.0);
}
vec3 CalcPointLight(PointLight light,vec3 normal,vec3 fragPos,vec3 viewDir)
{
    vec3 lightDir = normalize(light.position - fragPos);
    // 漫反射着色
    float diff = max(dot(normal, lightDir), 0.0);
    // 鏡面光着色
    vec3 reflectDir = reflect(-lightDir, normal);
    float spec = pow(max(dot(viewDir, reflectDir), 0.0), material.shininess);
    // 衰減
    float distance    = length(light.position - fragPos);
    float attenuation = 1.0 / (light.constant + light.linear * distance + 
                 light.quadratic * (distance * distance));    
    // 合併結果
    vec3 ambient  = light.ambient  * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 diffuse  = light.diffuse  * diff * vec3(texture(material.texture_diffuse1, TexCoords));
    vec3 specular=light.specular*spec*vec3(texture(material.texture_specular1,TexCoords));
    //vec3 specular=light.specular*spec*vec3(0.5);
    ambient  *= attenuation;
    diffuse  *= attenuation;
    specular *= attenuation;
    return (ambient + diffuse + specular);
}

天空盒頂點着色器：

#version 330 core
layout(location=0)in vec3 aPos;
out vec3 TexCoords;
uniform mat4 projection;
uniform mat4 view;
void main()
{
	TexCoords=aPos;
	gl_Position=projection*view*vec4(aPos,1.0);
	gl_Position=gl_Position.xyww;
}

天空盒片段着色器：

#version 330 core
in vec3 TexCoords;
uniform samplerCube skybox;
out vec4 FragColor;
void main()
{
	FragColor=texture(skybox,TexCoords);
}