着色器 Shaders
着色器类
头文件
#ifndef SHADER_H
#define SHADER_H
#include <string>
class Shader {
public:
// 程序ID
unsigned int ID;
// 构造函数
Shader(const char* vertexPath, const char* 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:
// 检查编译
void checkCompileErrors(unsigned int shader, std::string type);
};
#endif
cpp 文件
#include "Shader.hpp"
#include <iostream>
#include <fstream>
#include <sstream>
#include <glad/glad.h>
Shader::Shader(const char* vertexPath, const char* fragmentPath) {
// 得到着色器的代码
std::string vertexCode, fragmentCode;
std::ifstream vShaderFile, fShaderFile;
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;
// read file's buffer contents into streams
vShaderStream << vShaderFile.rdbuf();
fShaderStream << fShaderFile.rdbuf();
// close file handlers
vShaderFile.close();
fShaderFile.close();
// convert stream into string
vertexCode = vShaderStream.str();
fragmentCode = fShaderStream.str();
}
catch (std::ifstream::failure& e)
{
std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ: " << e.what() << std::endl;
}
const char* vShaderCode = vertexCode.c_str();
const char* fShaderCode = fragmentCode.c_str();
// 编译着色器
unsigned int vertex, fragment;
// 顶点着色器
vertex = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex, 1, &vShaderCode, NULL);
glCompileShader(vertex);
checkCompileErrors(vertex, "VERTEX");
// 片段着色器
fragment = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment, 1, &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
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[1024];
if (type != "PROGRAM")
{
glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(shader, 1024, 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, 1024, NULL, infoLog);
std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
}
}
}
练习
练习一
使用uniform定义一个水平偏移量，在顶点着色器中使用这个偏移量使三角形作平移动画
#version 460 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
out vec3 ourColor;
uniform float offset;
void main()
{
gl_Position = vec4(aPos.x + offset, aPos.y, aPos.z, 1.0f);
ourColor = aColor;
};
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "Shader.hpp"
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//------------------------------
Shader shader1("vertexShaderSource.vs", "fragmentShaderSource1.fs");
Shader shader2("vertexShaderSource.vs", "fragmentShaderSource2.fs");
// --------------------------------
// 画三角形
float firstTriangle[] = {
// 位置 //颜色
0.5f, -0.7f, 0.0f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.7f, 0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.9f, 0.0f, 0.0f, 0.0f, 1.0f
};
float secondTriangle[] = {
0.9f, -0.2f, 0.0f, 0.0f, 0.0f, 1.0f,
0.0f, 0.7f, 0.0f, 0.0f, 1.0f, 0.0f,
-0.7f, -0.4f, 0.0f, 1.0f, 0.0f, 0.0f
};
// 创建VBO，VAO
unsigned int VBO[2], VAO[2];
glGenVertexArrays(2, VAO);
glGenBuffers(2, VBO);
// ----- 第一个三角形 ------
// 绑定VAO
glBindVertexArray(VAO[0]);
// 复制顶点数组到缓冲中供OpenGL使用
glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(firstTriangle), firstTriangle, GL_STATIC_DRAW);
// 设置顶点属性指针
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 颜色属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// ----- 第二个三角形 ------
// 绑定VAO
glBindVertexArray(VAO[1]);
// 复制顶点数组到缓冲中供OpenGL使用
glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(secondTriangle), secondTriangle, GL_STATIC_DRAW);
// 设置顶点属性指针
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 颜色属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// 解绑
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
// 线框模式
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
// 渲染循环
while (!glfwWindowShouldClose(window))
{
// 输入
processInput(window);
// 渲染
glClearColor(0.5f, 0.5f, 0.2f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// 画三角形
glUseProgram(shader1.ID);
float timeValue = glfwGetTime();
float offset = sin(timeValue) / 2.0f;
int vertexOffsetLocation = glGetUniformLocation(shader1.ID, "offset");
glUniform1f(vertexOffsetLocation, offset);
glBindVertexArray(VAO[0]);
glDrawArrays(GL_TRIANGLES, 0, 3);
glUseProgram(shader2.ID);
vertexOffsetLocation = glGetUniformLocation(shader2.ID, "offset");
glUniform1f(vertexOffsetLocation, -offset);
glBindVertexArray(VAO[1]);
glDrawArrays(GL_TRIANGLES, 0, 3);
//glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
// 检查并调用事件，交换缓冲
glfwSwapBuffers(window);
glfwPollEvents();
}
// 删除VAO，VBO与着色器程序性
glDeleteVertexArrays(1, &VAO[0]);
glDeleteBuffers(1, &VBO[0]);
glDeleteVertexArrays(1, &VAO[1]);
glDeleteBuffers(1, &VBO[1]);
glDeleteProgram(shader1.ID);
glDeleteProgram(shader2.ID);
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS)
std::cout << "space is pressed" << std::endl;
}
运行结果：
练习二
使用out关键字把顶点位置输出到片段着色器，并将片段的颜色设置为与顶点位置相等（来看看连顶点位置值都在三角形中被插值的结果）。做完这些后，尝试回答下面的问题：为什么在三角形的左下角是黑的?
#version 460 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
out vec3 ourColor;
void main()
{
gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0f);
ourColor = aColor;
};
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "Shader.hpp"
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow* window);
int main() {
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//------------------------------
Shader shader1("vertexShaderSource.vs", "fragmentShaderSource1.fs");
Shader shader2("vertexShaderSource.vs", "fragmentShaderSource2.fs");
// --------------------------------
// 画三角形
float firstTriangle[] = {
// 位置 //颜色
0.5f, -0.7f, 0.0f, 1.0f, 0.0f, 0.0f,
-0.5f, -0.7f, 0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.9f, 0.0f, 0.0f, 0.0f, 1.0f
};
float secondTriangle[] = {
0.9f, -0.2f, 0.0f, 0.0f, 0.0f, 1.0f,
0.0f, 0.7f, 0.0f, 0.0f, 1.0f, 0.0f,
-0.7f, -0.4f, 0.0f, 1.0f, 0.0f, 0.0f
};
// 创建VBO，VAO
unsigned int VBO[2], VAO[2];
glGenVertexArrays(2, VAO);
glGenBuffers(2, VBO);
// ----- 第一个三角形 ------
// 绑定VAO
glBindVertexArray(VAO[0]);
// 复制顶点数组到缓冲中供OpenGL使用
glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(firstTriangle), firstTriangle, GL_STATIC_DRAW);
// 设置顶点属性指针
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 颜色属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(1);
// ----- 第二个三角形 ------
// 绑定VAO
glBindVertexArray(VAO[1]);
// 复制顶点数组到缓冲中供OpenGL使用
glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(secondTriangle), secondTriangle, GL_STATIC_DRAW);
// 设置顶点属性指针
// 位置属性
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// 颜色属性
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
glEnableVertexAttribArray(1);
// 解绑
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
// 线框模式
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
// 渲染循环
while (!glfwWindowShouldClose(window))
{
// 输入
processInput(window);
// 渲染
glClearColor(0.5f, 0.5f, 0.2f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// 画三角形
glUseProgram(shader1.ID);
glBindVertexArray(VAO[0]);
glDrawArrays(GL_TRIANGLES, 0, 3);
glUseProgram(shader2.ID);
glBindVertexArray(VAO[1]);
glDrawArrays(GL_TRIANGLES, 0, 3);
//glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
// 检查并调用事件，交换缓冲
glfwSwapBuffers(window);
glfwPollEvents();
}
// 删除VAO，VBO与着色器程序性
glDeleteVertexArrays(1, &VAO[0]);
glDeleteBuffers(1, &VBO[0]);
glDeleteVertexArrays(1, &VAO[1]);
glDeleteBuffers(1, &VBO[1]);
glDeleteProgram(shader1.ID);
glDeleteProgram(shader2.ID);
glfwTerminate();
return 0;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS)
std::cout << "space is pressed" << std::endl;
}
运行结果：
三角形左下角坐标中 x , y x,y x,y 均为负值，而颜色 rgb 只能为 0 到 1 的正值，所以左下角顶点颜色为 (0,0,0)，即黑色。
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