七、畫一個 3D 的彩色的立方體
阿新 • • 發佈：2018-11-10
畫完會動的 3D 矩形，現在玩點高階的，畫一個會動的 3D 彩色的立方體。
一、程式碼
- main.cpp
#include <iostream>
//GLEW
#define GLEW_STATIC
#include <GL/glew.h>
//GLFW
#include <GLFW/glfw3.h>
//Shader
#include "Shader.h"
// SOIL2
//Linux 用的是 \, 但是 / 都可以用
#include "SOIL2/SOIL2.h"
#include "SOIL2/stb_image.h" - Shader.h
#pragma once
//#ifndef shader_hpp
//#define shader_hpp
//#endif /* shader_hpp */
#include<string>
#include<fstream> //可以開啟檔案
#include<sstream>
#include<iostream>
#include<GL/glew.h>
class Shader {
GLuint vertex, fragment;
public:
GLuint Program;
Shader(const GLchar * vertexPath, const GLchar * fragmentPath)
{
std::string vertexCode;
std::string fragmentCode;
std::ifstream vShaderFile;
std::ifstream fShaderFile;
vShaderFile.exceptions(std::ifstream::badbit);
fShaderFile.exceptions(std::ifstream::badbit);
try {
vShaderFile.open(vertexPath);
fShaderFile.open(fragmentPath);
std::stringstream vShaderStream, fShaderStream;
vShaderStream << vShaderFile.rdbuf();
fShaderStream << fShaderFile.rdbuf();
//檔案關閉順序，先 v 再 f
vShaderFile.close();
fShaderFile.close();
vertexCode = vShaderStream.str();
fragmentCode = fShaderStream.str();
}
catch (std::ifstream::failure a) {
std::cout <<
"ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ"
<< std::endl;
}
//型別轉換
const GLchar *vShaderCode = vertexCode.c_str();
const GLchar *fShaderCode = fragmentCode.c_str();
//import and compile the shader
vertex = glCreateShader(GL_VERTEX_SHADER); //不用重新定義
glShaderSource(vertex, 1, &vShaderCode, NULL);
glCompileShader(vertex); //編譯
GLint success;
GLchar infoLog[512];
glGetShaderiv(vertex, GL_COMPILE_STATUS, &success); //編譯是否完成的位置
if (!success) {
glGetShaderInfoLog(vertex, 512, NULL, infoLog);
std::cout <<
"ERROR::SHADER::VERTEX::COMPILATION_FAILED\n"
<< infoLog << std::endl;
}
//邊緣調色器
fragment = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment, 1, &fShaderCode, NULL);
glCompileShader(fragment); //編譯
glGetShaderiv(fragment, GL_COMPILE_STATUS, &success); //編譯是否完成的位置
if (!success) {
glGetShaderInfoLog(fragment, 512, NULL, infoLog);
std::cout <<
"ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n"
<< infoLog << std::endl;
}
//create the program and link the program
this->Program = glCreateProgram(); //建立著色器程式
glAttachShader(this->Program, vertex);
glAttachShader(this->Program, fragment);
glLinkProgram(this->Program); //連結
glValidateProgram(this->Program); //可省略
glGetProgramiv(this->Program, GL_LINK_STATUS, &success);
if (!success) {
glGetProgramInfoLog(this->Program, 512, NULL, infoLog); //獲取連結情況
std::cout <<
"ERROR::SHADER::PROGRAM::LINKING_FAILED\n" <<
infoLog << std::endl;
}
}
~Shader() {
glDetachShader(this->Program, vertex);
glDetachShader(this->Program, fragment);
glDeleteShader(vertex);
glDeleteShader(fragment);
glDeleteProgram(this->Program);
}
void Use() {
glUseProgram(this->Program);
}
};
- core1.vs
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;
out vec3 Color;
uniform mat4 transform;
void main(){
gl_Position = transform * vec4(position, 1.0f);
Color = color;
}
- core1.frag
#version 330 core
in vec3 Color;
out vec4 color;
void main(){
color = vec4(Color, 0.8f);
}
程式正常執行，應該能出現一個 3D 彩色動態的立方體在轉。
其實這個立方體是繞著（1,1,1）在轉動的。
二、講解
設定頂點屬性指標。
//set the attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), (GLvoid *)0); //0:對應調色器裡 location 的值；3:對應 vec3 三個量；GL_FLOAT:浮點型；GL_FALSE:；5*sizeof(GLfloat):對應 Buffer 裡傳的資料；(GLvoid*)0:從第 0 個位置開始
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE,
6 * sizeof(GLfloat), (GLvoid *)(