OpenGL基礎 通過矩陣操作，將影象進行移動旋轉
阿新 • • 發佈：2019-02-14
main.cpp
#define STB_IMAGE_IMPLEMENTATION
#include <glad/glad.h>
#include <glad/glad.c>
#include <GLFW/glfw3.h>
#include <stb_image.h>
#include <iostream>
#include "shader.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp> shader.h
#ifndef SHADER_H
#define SHADER_H
#include <glad/glad.h>; // 包含glad來獲取所有的必須OpenGL標頭檔案
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
class Shader
{
public:
// 程式ID
unsigned int m_ID;
// 構造器讀取並構建著色器
Shader(const GLchar* vertexPath, const GLchar* fragmentPath);
// 使用/啟用程式
void useShaderProgram();
// uniform工具函式
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;
void setMat4(const std::string &name, glm::mat4 mat) const;
private:
void checkCompileErrors(unsigned int shader, std::string type);
};
#endifshader.cpp
#include "shader.h"
Shader::Shader(const char* vertexPath, const char* fragmentPath)
{
// 1. retrieve the vertex/fragment source code from filePath
// 載入讀取Shader檔案
std::string strVertexCode;
std::string strFragmentCode;
std::ifstream vShaderFile;
std::ifstream fShaderFile;
// ensure ifstream objects can throw exceptions:
vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
try
{
// open files
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
strVertexCode = vShaderStream.str();
strFragmentCode = fShaderStream.str();
}
catch (std::ifstream::failure e)
{
std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
}
const char* vShaderCode = strVertexCode.c_str();
const char * fShaderCode = strFragmentCode.c_str();
// 2. compile shaders 編譯
unsigned int nVertex, nFragment;
int nSuccess = 0;
char infoLog[512];
// vertex shader
nVertex = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(nVertex, 1, &vShaderCode, NULL);
glCompileShader(nVertex);
checkCompileErrors(nVertex, "VERTEX");
// fragment Shader
nFragment = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(nFragment, 1, &fShaderCode, NULL);
glCompileShader(nFragment);
checkCompileErrors(nFragment, "FRAGMENT");
// shader Program
m_ID = glCreateProgram();
glAttachShader(m_ID, nVertex);
glAttachShader(m_ID, nFragment);
glLinkProgram(m_ID);
checkCompileErrors(m_ID, "PROGRAM");
// delete the shaders as they're linked into our program now and no longer necessary
glDeleteShader(nVertex);
glDeleteShader(nFragment);
}
// activate the shader
// ------------------------------------------------------------------------
void Shader::useShaderProgram()
{
glUseProgram(m_ID);
}
// utility uniform functions
// ------------------------------------------------------------------------
void Shader::setBool(const std::string &name, bool value) const
{
glUniform1i(glGetUniformLocation(m_ID, name.c_str()), (int)value);
}
// ------------------------------------------------------------------------
void Shader::setInt(const std::string &name, int value) const
{
glUniform1i(glGetUniformLocation(m_ID, name.c_str()), value);
}
// ------------------------------------------------------------------------
void Shader::setFloat(const std::string &name, float value) const
{
glUniform1f(glGetUniformLocation(m_ID, name.c_str()), value);
}
void Shader::setMat4(const std::string &name, glm::mat4 mat) const
{
glUniformMatrix4fv(glGetUniformLocation(m_ID, name.c_str()), 1, GL_FALSE, &mat[0][0]);
}
// utility function for checking shader compilation/linking errors.
// ------------------------------------------------------------------------
void Shader::checkCompileErrors(unsigned int shader, std::string type)
{
int nSuccess = 0;
char infoLog[1024];
if (type != "PROGRAM")
{
glGetShaderiv(shader, GL_COMPILE_STATUS, &nSuccess);
if (!nSuccess)
{
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, &nSuccess);
if (!nSuccess)
{
glGetProgramInfoLog(shader, 1024, NULL, infoLog);
std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
}
}
}coordinate_systems.vs
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 texturePos;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
out vec2 TexCoord;
void main()
{
// 注意乘法要從右向左讀
gl_Position = projection * view * model * vec4(aPos, 1.0);
TexCoord = vec2(texturePos.x, 1.0 - texturePos.y);
}
coordinate_systems.fs
#version 330 core // 版本宣告
out vec4 FragColor; // 輸出繪製
in vec2 TexCoord; // 從vs中傳進
uniform sampler2D texture1; // 紋理取樣器
uniform sampler2D texture2; // 紋理取樣器
void main()
{
// 兩個紋理進行混合
FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.5);
}
