3D软件渲染教程：透视

本是古典何须时尚 2022-09-04 15:54 231阅读 0赞

# 上篇文章的结果 #

![在这里插入图片描述][491f0e05cbf642de9a05dcb15e05f1f2.gif_pic_center]

# 修改Stars.java #

/**
     *
     * @author yangshuohao
     */
    public class Stars3D 
    {
        
        private final float m_spread;
        private final float m_speed;
        
        private final float m_starX[];
        private final float m_starY[];
        private final float m_starZ[];
        
        public Stars3D(int numStars,float spread,float speed)
        {
        
            m_spread=spread;
            m_speed=speed;
            
            m_starX=new float[numStars];
            m_starY=new float[numStars];
            m_starZ=new float[numStars];
    
            for(int i=0;i<m_starX.length;i++)
            {
        
                InitStar(i);
            }
        }
        
        private void InitStar(int i)
        {
        
            m_starX[i]=2 * ((float)Math.random()-0.5f)*m_spread;
            m_starY[i]=2 * ((float)Math.random()-0.5f)*m_spread;
            m_starZ[i]=((float)Math.random()+0.00001f)*m_spread;              
        }
    
        public void UpdateAndRender(Bitmap target,float delta)
        {
        
            target.Clear((byte)0x00);
            
            float halfWidth=target.GetWidth()/2.0f;
            float halfHeight=target.GetHeight()/2.0f;
    
            for(int i=0;i<m_starX.length;i++)
            {
        
                m_starZ[i]-=delta*m_speed;
                
                if(m_starZ[i] <=0 )
                {
        
                    InitStar(i);
                }           
                
                int x=(int)((m_starX[i])*halfWidth+halfWidth);
                int y=(int)((m_starY[i])*halfHeight+halfHeight);
    
                if(x<0 || x>=target.GetWidth() || (y<0 || y>=target.GetHeight()))
                {
        
                    InitStar(i);
                }
                else
                {
        
                    target.DrawPixel(x, y, (byte)0xff, (byte)0xff, (byte)0xff, (byte)0xff);
                }
            }
        }
    }

结果：  
![在这里插入图片描述][e0925b647eef42b1a0524e54a6b6a516.gif_pic_center]  
为什么会产生这样的结果呢？其实这就是透视的原因，有关透视可以参考[这篇文章][Link 1]。  
最后修改Stars.java

/**
     *
     * @author yangshuohao
     */
    public class Stars3D 
    {
        
        private final float m_spread;
        private final float m_speed;
        
        private final float m_starX[];
        private final float m_starY[];
        private final float m_starZ[];
        
        public Stars3D(int numStars,float spread,float speed)
        {
        
            m_spread=spread;
            m_speed=speed;
            
            m_starX=new float[numStars];
            m_starY=new float[numStars];
            m_starZ=new float[numStars];
    
            for(int i=0;i<m_starX.length;i++)
            {
        
                InitStar(i);
            }
        }
        
        private void InitStar(int i)
        {
        
            m_starX[i]=2 * ((float)Math.random()-0.5f)*m_spread;
            m_starY[i]=2 * ((float)Math.random()-0.5f)*m_spread;
            m_starZ[i]=((float)Math.random()+0.00001f)*m_spread;              
        }
    
        public void UpdateAndRender(Bitmap target,float delta)
        {
        
            final float tanHalfFov=(float)Math.tan(Math.toRadians(140.0/2.0));
            target.Clear((byte)0x00);
            
            float halfWidth=target.GetWidth()/2.0f;
            float halfHeight=target.GetHeight()/2.0f;
    
            for(int i=0;i<m_starX.length;i++)
            {
        
                m_starZ[i]-=delta*m_speed;
                
                if(m_starZ[i] <=0 )
                {
        
                    InitStar(i);
                }
                
                int x=(int)((m_starX[i]/(m_starZ[i]*tanHalfFov))*halfWidth+halfWidth);
                int y=(int)((m_starY[i]/(m_starZ[i]*tanHalfFov))*halfHeight+halfHeight);
                
                
                //int x=(int)((m_starX[i])*halfWidth+halfWidth);
                //int y=(int)((m_starY[i])*halfHeight+halfHeight);
    
                if(x<0 || x>=target.GetWidth() || (y<0 || y>=target.GetHeight()))
                {
        
                    InitStar(i);
                }
                else
                {
        
                    target.DrawPixel(x, y, (byte)0xff, (byte)0xff, (byte)0xff, (byte)0xff);
                }
            }
        }
    }

效果：  
![在这里插入图片描述][14364f3be16c4499bf3bc3058dc82123.gif_pic_center]

[491f0e05cbf642de9a05dcb15e05f1f2.gif_pic_center]: /images/20220829/abd5bd9f29b841b2928cd612d69828ff.png
[e0925b647eef42b1a0524e54a6b6a516.gif_pic_center]: /images/20220829/1ef7277c86c648309f55c8fc6c793970.png
[Link 1]: https://yangshuohao.blog.csdn.net/article/details/119566196
[14364f3be16c4499bf3bc3058dc82123.gif_pic_center]: /images/20220829/2a7697903bfa4c01b3f7b3cda82df457.png