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C++中使用OpenGL绘制小屋的实现算法
2023-07-04 19:41:23 深夜i     16     0
C++ OpenGL 绘制 小屋 实现算法

OpenGL是一种用于绘制三维图形的API，它是跨平台的，可以在多个操作系统上使用。在学习OpenGL的过程中，绘制一个小屋是一个很常见的练习。

实现算法：

1. 初始化OpenGL环境。

2. 绘制地面，这个可以用一个平面来实现。

3. 使用三角形绘制房顶，三角形的三个点坐标为（0,1,0）、（-1,0,0）和（1,0,0）。

4. 绘制四面墙体。分别使用四个矩形来绘制。

5. 绘制门和窗户。门和窗户可以通过使用两个梯形来实现。

6. 绘制屋顶的两个烟囱，可以通过使用两个立方体来实现，然后对其中一面进行旋转。

具体实现流程：

1. 引入需要的OpenGL和GLUT库。

#include <stdlib.h>
#include <GL/glut.h>

2. 设置视角和显示模式。

void reshape(int w,int h){
  glViewport(0,0,w,h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(45.0,(double)w/(double)h,1.0,200.0); 
}

3. 绘制地面。

void drawGround()
{
  glBegin(GL_QUADS);
    glVertex3f(-20.0f, 0.0f, -20.0f);
    glVertex3f(-20.0f, 0.0f, 20.0f);
    glVertex3f(20.0f, 0.0f, 20.0f);
    glVertex3f(20.0f, 0.0f, -20.0f);
  glEnd();
}

4. 绘制三角形的房顶和四面墙体。

void drawRoof()
{
  glBegin(GL_TRIANGLES);
    glVertex3f(0.0f, 1.0f, 0.0f);
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(1.0f, 0.0f, 0.0f);
  glEnd();
}
void drawWall()
{
  glBegin(GL_QUADS);
    //front wall
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(-1.0f, 0.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, 0.0f);
    
    //back wall
    glVertex3f(-1.0f,0.0f,-1.0f);
    glVertex3f(-1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,0.0f,-1.0f);
    //right wall
    glVertex3f(1.0f,0.0f,-1.0f);
    glVertex3f(1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,1.0f,0.0f);
    glVertex3f(1.0f,0.0f,0.0f);
    //left wall
    glVertex3f(1.0f,0.0f,0.0f);
    glVertex3f(1.0f,1.0f,0.0f);
    glVertex3f(-1.0f,1.0f,0.0f);
    glVertex3f(-1.0f,0.0f,0.0f);
  glEnd();
}

5. 绘制门和窗户。

void drawDoor()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.3f, 0.0f, 0.02f);
    glVertex3f(-0.3f, 0.6f, 0.02f);
    glVertex3f(0.3f, 0.6f, 0.02f);
    glVertex3f(0.3f, 0.0f, 0.02f);
  glEnd();
}
void drawWindow()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.8f, 0.4f, 0.0f);
    glVertex3f(-0.8f, 0.8f, 0.0f);
    glVertex3f(-0.4f, 0.8f, 0.0f);
    glVertex3f(-0.4f, 0.4f, 0.0f);
  glEnd();
}

6. 绘制烟囱。

void drawChimney()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
  glEnd();
}

7. 显示绘制结果。

void display(void){
  glEnable(GL_DEPTH_TEST);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(0.0f, 0.0f, -15.0f);
  drawGround();
  drawRoof();
  drawWall();
  drawDoor();
  drawWindow();
  drawChimney();
  glutSwapBuffers(); 
}

完整代码如下：

#include <stdlib.h>
#include <GL/glut.h>
void reshape(int w,int h){
  glViewport(0,0,w,h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(45.0,(double)w/(double)h,1.0,200.0); 
}
void drawGround()
{
  glBegin(GL_QUADS);
    glVertex3f(-20.0f, 0.0f, -20.0f);
    glVertex3f(-20.0f, 0.0f, 20.0f);
    glVertex3f(20.0f, 0.0f, 20.0f);
    glVertex3f(20.0f, 0.0f, -20.0f);
  glEnd();
}
void drawRoof()
{
  glBegin(GL_TRIANGLES);
    glVertex3f(0.0f, 1.0f, 0.0f);
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(1.0f, 0.0f, 0.0f);
  glEnd();
}
void drawWall()
{
  glBegin(GL_QUADS);
    //front wall
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(-1.0f, 0.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, 0.0f);
    
    //back wall
    glVertex3f(-1.0f,0.0f,-1.0f);
    glVertex3f(-1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,0.0f,-1.0f);
    //right wall
    glVertex3f(1.0f,0.0f,-1.0f);
    glVertex3f(1.0f,1.0f,-1.0f);
    glVertex3f(1.0f,1.0f,0.0f);
    glVertex3f(1.0f,0.0f,0.0f);
    //left wall
    glVertex3f(1.0f,0.0f,0.0f);
    glVertex3f(1.0f,1.0f,0.0f);
    glVertex3f(-1.0f,1.0f,0.0f);
    glVertex3f(-1.0f,0.0f,0.0f);
  glEnd();
}
void drawDoor()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.3f, 0.0f, 0.02f);
    glVertex3f(-0.3f, 0.6f, 0.02f);
    glVertex3f(0.3f, 0.6f, 0.02f);
    glVertex3f(0.3f, 0.0f, 0.02f);
  glEnd();
}
void drawWindow()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.8f, 0.4f, 0.0f);
    glVertex3f(-0.8f, 0.8f, 0.0f);
    glVertex3f(-0.4f, 0.8f, 0.0f);
    glVertex3f(-0.4f, 0.4f, 0.0f);
  glEnd();
}
void drawChimney()
{
  glBegin(GL_QUADS);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(-0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.8f,0.2f);
    glVertex3f(0.2f,0.8f,-0.2f);
    glVertex3f(-0.2f,0.6f,-0.2f);
    glVertex3f(-0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,0.2f);
    glVertex3f(0.2f,0.6f,-0.2f);
  glEnd();
}
void display(void){
  glEnable(GL_DEPTH_TEST);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(0.0f, 0.0f, -15.0f);
  drawGround();
  drawRoof();
  drawWall();
  drawDoor();
  drawWindow();
  drawChimney();
  glutSwapBuffers(); 
}
int main(int argc,char** argv){
  glutInit(&argc,argv); //初始化
  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
  glutInitWindowSize(640,480); //窗口大小：640*480
  glutInitWindowPosition(100,100);//窗口位置：(100,100)
  glutCreateWindow("House");//创建名为‘House’的窗口
  glutDisplayFunc(display);//用于绘制窗口
  glutReshapeFunc(reshape);//用于更改窗口大小
  glutMainLoop();
  return 0;
}

运行代码后，可以在窗口中看到绘制出来的小屋。

绘制小屋的实现算法就介绍到这里。要绘制复杂的三维物体需要更多的OpenGL知识，可以继续学习OpenGL相关的知识。

  
  

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