[C++知识库]从零开始的openGL--cs游戏（2）Shader类，Texture2D类，ResourceManager类

Shader类，Texture2D类，ResourceManager类都是从learnopengl中复制过来的。主要是这些代码的确写的很好，基本没有修改的必要，我直接复制了。(￣_,￣ )

Shader类

#ifndef SHADER_H
#define SHADER_H

#include <string>

#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>


// General purpsoe shader object. Compiles from file, generates
// compile/link-time error messages and hosts several utility 
// functions for easy management.
class Shader
{
public:
    // state
    unsigned int ID;
    // constructor
    Shader();
    // sets the current shader as active
    Shader& Use();
    // compiles the shader from given source code
    void    Compile(const char* vertexSource, const char* fragmentSource, const char* geometrySource = nullptr); // note: geometry source code is optional 
    // utility functions
    void    SetFloat(const char* name, float value, bool useShader = false);
    void    SetInteger(const char* name, int value, bool useShader = false);
    void    SetVector2f(const char* name, float x, float y, bool useShader = false);
    void    SetVector2f(const char* name, const glm::vec2& value, bool useShader = false);
    void    SetVector3f(const char* name, float x, float y, float z, bool useShader = false);
    void    SetVector3f(const char* name, const glm::vec3& value, bool useShader = false);
    void    SetVector4f(const char* name, float x, float y, float z, float w, bool useShader = false);
    void    SetVector4f(const char* name, const glm::vec4& value, bool useShader = false);
    void    SetMatrix4(const char* name, const glm::mat4& matrix, bool useShader = false);
private:
    // checks if compilation or linking failed and if so, print the error logs
    void    checkCompileErrors(unsigned int object, std::string type);
};

#endif

#include "shader.h"

#include <iostream>


// constructor

inline Shader::Shader() { }

Shader& Shader::Use()
{
    glUseProgram(this->ID);
    return *this;
}

void Shader::Compile(const char* vertexSource, const char* fragmentSource, const char* geometrySource)
{
    unsigned int sVertex, sFragment, gShader;
    // vertex Shader
    sVertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(sVertex, 1, &vertexSource, NULL);
    glCompileShader(sVertex);
    checkCompileErrors(sVertex, "VERTEX");
    // fragment Shader
    sFragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(sFragment, 1, &fragmentSource, NULL);
    glCompileShader(sFragment);
    checkCompileErrors(sFragment, "FRAGMENT");
    // if geometry shader source code is given, also compile geometry shader
    if (geometrySource != nullptr)
    {
        gShader = glCreateShader(GL_GEOMETRY_SHADER);
        glShaderSource(gShader, 1, &geometrySource, NULL);
        glCompileShader(gShader);
        checkCompileErrors(gShader, "GEOMETRY");
    }
    // shader program
    this->ID = glCreateProgram();
    glAttachShader(this->ID, sVertex);
    glAttachShader(this->ID, sFragment);
    if (geometrySource != nullptr)
        glAttachShader(this->ID, gShader);
    glLinkProgram(this->ID);
    checkCompileErrors(this->ID, "PROGRAM");
    // delete the shaders as they're linked into our program now and no longer necessary
    glDeleteShader(sVertex);
    glDeleteShader(sFragment);
    if (geometrySource != nullptr)
        glDeleteShader(gShader);
}

void Shader::SetFloat(const char* name, float value, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform1f(glGetUniformLocation(this->ID, name), value);
}
void Shader::SetInteger(const char* name, int value, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform1i(glGetUniformLocation(this->ID, name), value);
}
void Shader::SetVector2f(const char* name, float x, float y, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform2f(glGetUniformLocation(this->ID, name), x, y);
}
void Shader::SetVector2f(const char* name, const glm::vec2& value, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform2f(glGetUniformLocation(this->ID, name), value.x, value.y);
}
void Shader::SetVector3f(const char* name, float x, float y, float z, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform3f(glGetUniformLocation(this->ID, name), x, y, z);
}
void Shader::SetVector3f(const char* name, const glm::vec3& value, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform3f(glGetUniformLocation(this->ID, name), value.x, value.y, value.z);
}
void Shader::SetVector4f(const char* name, float x, float y, float z, float w, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform4f(glGetUniformLocation(this->ID, name), x, y, z, w);
}
void Shader::SetVector4f(const char* name, const glm::vec4& value, bool useShader)
{
    if (useShader)
        this->Use();
    glUniform4f(glGetUniformLocation(this->ID, name), value.x, value.y, value.z, value.w);
}
void Shader::SetMatrix4(const char* name, const glm::mat4& matrix, bool useShader)
{
    if (useShader)
        this->Use();
    glUniformMatrix4fv(glGetUniformLocation(this->ID, name), 1, false, glm::value_ptr(matrix));
}


void Shader::checkCompileErrors(unsigned int object, std::string type)
{
    int success;
    char infoLog[1024];
    if (type != "PROGRAM")
    {
        glGetShaderiv(object, GL_COMPILE_STATUS, &success);
        if (!success)
        {
            glGetShaderInfoLog(object, 1024, NULL, infoLog);
            std::cout << "| ERROR::SHADER: Compile-time error: Type: " << type << "\n"
                << infoLog << "\n -- --------------------------------------------------- -- "
                << std::endl;
        }
    }
    else
    {
        glGetProgramiv(object, GL_LINK_STATUS, &success);
        if (!success)
        {
            glGetProgramInfoLog(object, 1024, NULL, infoLog);
            std::cout << "| ERROR::Shader: Link-time error: Type: " << type << "\n"
                << infoLog << "\n -- --------------------------------------------------- -- "
                << std::endl;
        }
    }
}

Texture类

#ifndef TEXTURE_H
#define TEXTURE_H

#include <glad/glad.h>

// Texture2D is able to store and configure a texture in OpenGL.
// It also hosts utility functions for easy management.
class Texture2D
{
public:
    // holds the ID of the texture object, used for all texture operations to reference to this particlar texture
    unsigned int ID;
    // texture image dimensions
    unsigned int Width, Height; // width and height of loaded image in pixels
    // texture Format
    unsigned int Internal_Format; // format of texture object
    unsigned int Image_Format; // format of loaded image
    // texture configuration
    unsigned int Wrap_S; // wrapping mode on S axis
    unsigned int Wrap_T; // wrapping mode on T axis
    unsigned int Filter_Min; // filtering mode if texture pixels < screen pixels
    unsigned int Filter_Max; // filtering mode if texture pixels > screen pixels
    // constructor (sets default texture modes)
    Texture2D();
    // generates texture from image data
    void Generate(unsigned int width, unsigned int height, unsigned char* data);
    // binds the texture as the current active GL_TEXTURE_2D texture object
    void Bind() const;
};

#endif

#include <iostream>

#include "Texture.h"


Texture2D::Texture2D()
    : Width(0), Height(0), Internal_Format(GL_RGB), Image_Format(GL_RGB), Wrap_S(GL_REPEAT), Wrap_T(GL_REPEAT), Filter_Min(GL_LINEAR), Filter_Max(GL_LINEAR)
{
    glGenTextures(1, &this->ID);
}

void Texture2D::Generate(unsigned int width, unsigned int height, unsigned char* data)
{
    this->Width = width;
    this->Height = height;
    // create Texture
    glBindTexture(GL_TEXTURE_2D, this->ID);
    glTexImage2D(GL_TEXTURE_2D, 0, this->Internal_Format, width, height, 0, this->Image_Format, GL_UNSIGNED_BYTE, data);
    // set Texture wrap and filter modes
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, this->Wrap_S);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, this->Wrap_T);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, this->Filter_Min);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, this->Filter_Max);
    // unbind texture
    glBindTexture(GL_TEXTURE_2D, 0);
}

void Texture2D::Bind() const
{
    glBindTexture(GL_TEXTURE_2D, this->ID);
}

ResourceManager类

#ifndef RESOURCE_MANAGER_H
#define RESOURCE_MANAGER_H

#include <map>
#include <string>

#include <glad/glad.h>

#include "Texture.h"
#include "Shader.h"


// A static singleton ResourceManager class that hosts several
// functions to load Textures and Shaders. Each loaded texture
// and/or shader is also stored for future reference by string
// handles. All functions and resources are static and no 
// public constructor is defined.
class ResourceManager
{
public:
    // resource storage
    static std::map<std::string, Shader>    Shaders;
    static std::map<std::string, Texture2D> Textures;
    // loads (and generates) a shader program from file loading vertex, fragment (and geometry) shader's source code. If gShaderFile is not nullptr, it also loads a geometry shader
    static Shader    LoadShader(const char* vShaderFile, const char* fShaderFile, const char* gShaderFile, std::string name);
    // retrieves a stored sader
    static Shader    GetShader(std::string name);
    // loads (and generates) a texture from file
    static Texture2D LoadTexture(const char* file, bool alpha, std::string name);
    // retrieves a stored texture
    static Texture2D GetTexture(std::string name);
    // properly de-allocates all loaded resources
    static void      Clear();
private:
    // private constructor, that is we do not want any actual resource manager objects. Its members and functions should be publicly available (static).
    ResourceManager() { }
    // loads and generates a shader from file
    static Shader    loadShaderFromFile(const char* vShaderFile, const char* fShaderFile, const char* gShaderFile = nullptr);
    // loads a single texture from file
    static Texture2D loadTextureFromFile(const char* file, bool alpha);
};

#endif

#include "ResourceManager.h"
#include <iostream>
#include <sstream>
#include <fstream>

#include "stb_image.h"

// Instantiate static variables
std::map<std::string, Texture2D>    ResourceManager::Textures;
std::map<std::string, Shader>       ResourceManager::Shaders;


Shader ResourceManager::LoadShader(const char* vShaderFile, const char* fShaderFile, const char* gShaderFile, std::string name)
{
    Shaders[name] = loadShaderFromFile(vShaderFile, fShaderFile, gShaderFile);
    return Shaders[name];
}

Shader ResourceManager::GetShader(std::string name)
{
    return Shaders[name];
}

Texture2D ResourceManager::LoadTexture(const char* file, bool alpha, std::string name)
{
    Textures[name] = loadTextureFromFile(file, alpha);
    return Textures[name];
}

Texture2D ResourceManager::GetTexture(std::string name)
{
    return Textures[name];
}

void ResourceManager::Clear()
{
    // (properly) delete all shaders	
    for (auto iter : Shaders)
        glDeleteProgram(iter.second.ID);
    // (properly) delete all textures
    for (auto iter : Textures)
        glDeleteTextures(1, &iter.second.ID);
}

Shader ResourceManager::loadShaderFromFile(const char* vShaderFile, const char* fShaderFile, const char* gShaderFile)
{
    // 1. retrieve the vertex/fragment source code from filePath
    std::string vertexCode;
    std::string fragmentCode;
    std::string geometryCode;
    try
    {
        // open files
        std::ifstream vertexShaderFile(vShaderFile);
        std::ifstream fragmentShaderFile(fShaderFile);
        std::stringstream vShaderStream, fShaderStream;
        // read file's buffer contents into streams
        vShaderStream << vertexShaderFile.rdbuf();
        fShaderStream << fragmentShaderFile.rdbuf();
        // close file handlers
        vertexShaderFile.close();
        fragmentShaderFile.close();
        // convert stream into string
        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
        // if geometry shader path is present, also load a geometry shader
        if (gShaderFile != nullptr)
        {
            std::ifstream geometryShaderFile(gShaderFile);
            std::stringstream gShaderStream;
            gShaderStream << geometryShaderFile.rdbuf();
            geometryShaderFile.close();
            geometryCode = gShaderStream.str();
        }
    }
    catch (std::exception e)
    {
        std::cout << "ERROR::SHADER: Failed to read shader files" << std::endl;
    }
    const char* vShaderCode = vertexCode.c_str();
    const char* fShaderCode = fragmentCode.c_str();
    const char* gShaderCode = geometryCode.c_str();
    // 2. now create shader object from source code
    Shader shader;
    shader.Compile(vShaderCode, fShaderCode, gShaderFile != nullptr ? gShaderCode : nullptr);
    return shader;
}

Texture2D ResourceManager::loadTextureFromFile(const char* file, bool alpha)
{
    // create texture object
    Texture2D texture;
    if (alpha)
    {
        texture.Internal_Format = GL_RGBA;
        texture.Image_Format = GL_RGBA;
    }
    // load image
    int width, height, nrChannels;
    unsigned char* data = stbi_load(file, &width, &height, &nrChannels, 0);
    // now generate texture
    texture.Generate(width, height, data);
    // and finally free image data
    stbi_image_free(data);
    return texture;
}