学习自:
https://learnopengl-cn.github.io/01%20Getting%20started/05%20Shaders/#_7
首先放一张效果图:
本次教程,将着色器单独定义了一个类,方便代码阅读与编写。
1,首先新建要给shader类:shader_s.h
(1)shader_s.h
#ifndef SHADER_H
#define SHADER_H #include <glad/glad.h> // 包含glad来获取所有的必须OpenGL头文件 #include <string>
#include <fstream>
#include <sstream>
#include <iostream> class Shader
{
public:
// 程序ID
unsigned int ID; // 构造器读取并构建着色器
Shader(const GLchar* vertexPath, const GLchar* fragmentPath);
// 使用/激活程序
void use();
// uniform工具函数
void setBool(const std::string &name, bool value) const;
void setInt(const std::string &name, int value) const;
void setFloat(const std::string &name, float value) const;
private:
void checkCompileErrors(unsigned int shader, std::string type);
}; #endif
(2)将头文件中的方法逐一实现
注意的是,我们类的写法,与链接中的写法有不同之处。
#include "shader_s.h" Shader::Shader(const GLchar * vertexPath, const GLchar * fragmentPath)
{
// 1. 从文件路径中获取顶点/片段着色器
std::string vertexCode;
std::string fragmentCode;
std::ifstream vShaderFile;
std::ifstream fShaderFile;
// 保证ifstream对象可以抛出异常:
vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
try
{
// 打开文件
vShaderFile.open(vertexPath);
fShaderFile.open(fragmentPath);
std::stringstream vShaderStream, fShaderStream;
// 读取文件的缓冲内容到数据流中
vShaderStream << vShaderFile.rdbuf();
fShaderStream << fShaderFile.rdbuf();
// 关闭文件处理器
vShaderFile.close();
fShaderFile.close();
// 转换数据流到string
vertexCode = vShaderStream.str();
fragmentCode = fShaderStream.str();
}
catch (std::ifstream::failure e)
{
std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
}
const char* vShaderCode = vertexCode.c_str();
const char * fShaderCode = fragmentCode.c_str();
// 2. 编译着色器
unsigned int vertex, fragment;
// 顶点着色器 vs
vertex = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex, , &vShaderCode, NULL);
glCompileShader(vertex);
checkCompileErrors(vertex, "VERTEX");
// 片段着色器 fs
fragment = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment, , &fShaderCode, NULL);
glCompileShader(fragment);
checkCompileErrors(fragment, "FRAGMENT");
// 着色器程序
ID = glCreateProgram();
glAttachShader(ID, vertex);
glAttachShader(ID, fragment);
glLinkProgram(ID);
checkCompileErrors(ID, "PROGRAM");
// 删除着色器,它们已经链接到我们的程序中了,已经不再需要了 glDeleteShader(vertex);
glDeleteShader(fragment);
} void Shader::use()
{
glUseProgram(ID);
} void Shader::setBool(const std::string & name, bool value) const
{
glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
} void Shader::setInt(const std::string & name, int value) const
{
glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
} void Shader::setFloat(const std::string & name, float value) const
{
glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
} void Shader::checkCompileErrors(unsigned int shader, std::string type)
{
int success;
char infoLog[];
if (type != "PROGRAM")
{
glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(shader, , NULL, infoLog);
std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
}
}
else
{
glGetProgramiv(shader, GL_LINK_STATUS, &success);
if (!success)
{
glGetProgramInfoLog(shader, , NULL, infoLog);
std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
}
}
}
2,主程序的使用
注意,我们的50行,在使用类的构造方法时候,传入的两个字符串表示的是我们的两个本地文件地址,这两个文件,表示的是,我们的两个shader脚本,需要我们的手动创建,并且加入代码。
两个脚本在最后给出。
(1)主程序TestShader.cpp
有一点需要注意的是,在vs中,我们自定义的类,如果要引用,用的是双引号 “”
也就是 #include "shader_s.h" 跟链接中的也有区别
#include <glad/glad.h>
#include <GLFW/glfw3.h> #include "shader_s.h" #include <iostream> void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window); // settings
const unsigned int SCR_WIDTH = ;
const unsigned int SCR_HEIGHT = ; int main()
{
// glfw: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, );
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, );
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); #ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
#endif // glfw window creation
// --------------------
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); // glad: load all OpenGL function pointers
// ---------------------------------------
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -;
} // build and compile our shader program
// ------------------------------------
Shader ourShader("../res/shader.vs", "../res/shader.fs"); // you can name your shader files however you like // set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
// 位置信息 // 颜色信息
0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, // 右下
-0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, // 左下
0.0f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f // 顶部
}; unsigned int VBO, VAO;
glGenVertexArrays(, &VAO);
glGenBuffers(, &VBO);
//首先绑定顶点数组对象,然后绑定并设置顶点缓冲区,然后配置顶点属性。
glBindVertexArray(VAO); glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); // 位置属性
glVertexAttribPointer(, , GL_FLOAT, GL_FALSE, * sizeof(float), (void*));
glEnableVertexAttribArray();
// 颜色属性
glVertexAttribPointer(, , GL_FLOAT, GL_FALSE, * sizeof(float), (void*)( * sizeof(float)));
glEnableVertexAttribArray();
/*
glVertexAttribPointer 指定了渲染时索引值为 index 的顶点属性数组的数据格式和位置。
void glVertexAttribPointer( GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride,const GLvoid * pointer);
参数:
(1)index
指定要修改的顶点属性的索引值
(2)size
指定每个顶点属性的组件数量。必须为1、2、3或者4。初始值为4。(如position是由3个(x,y,z)组成,而颜色是4个(r,g,b,a))
(4)type
指定数组中每个组件的数据类型。可用的符号常量有GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,GL_UNSIGNED_SHORT, GL_FIXED, 和 GL_FLOAT,初始值为GL_FLOAT。
(5)normalized
指定当被访问时,固定点数据值是否应该被归一化(GL_TRUE)或者直接转换为固定点值(GL_FALSE)。
(6)stride
指定连续顶点属性之间的偏移量。如果为0,那么顶点属性会被理解为:它们是紧密排列在一起的。初始值为0。
(7)pointer
指定第一个组件在数组的第一个顶点属性中的偏移量。该数组与GL_ARRAY_BUFFER绑定,储存于缓冲区中。初始值为0;
*/ // 循环渲染
while (!glfwWindowShouldClose(window))
{
// input
// -----
processInput(window); // render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT); // render the triangle
ourShader.use();
glBindVertexArray(VAO);
glDrawArrays(GL_TRIANGLES, , ); // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
} // optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(, &VAO);
glDeleteBuffers(, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return ;
} // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
} // glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(, , width, height);
}
(2) 脚本编写
TestShader是我的项目名,然后新建文件夹res,存放我们的脚本,然后创建两个脚本,名字自己取就好,主程序中对应好就好了。
a)顶点着色器(Vetex Shader)shader.vs
#version core
layout (location = ) in vec3 aPos; // 位置变量的属性位置值为 0
layout (location = ) in vec3 aColor; // 颜色变量的属性位置值为 1 out vec3 ourColor; // 向片段着色器输出一个颜色 void main()
{
gl_Position = vec4(aPos, 1.0);
ourColor = aColor; // 将ourColor设置为我们从顶点数据那里得到的输入颜色
}
b)片段着色器(fragment Shader)shader.fs
#version core
out vec4 FragColor;
in vec3 ourColor; void main()
{
FragColor = vec4(ourColor, 1.0);
}
3,最后运行我们的程序,就可以得到下面的效果图: