上篇文章的结果

3D软件渲染教程：透视_i++

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：

3D软件渲染教程：透视_i++_02

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​​。

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：

3D软件渲染教程：透视_3d_03