3DSoftEngine/RenderContext.java at master · VigneshwarJ/3DSoftEngine · GitHub

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/**
 * RenderContext
 */
public class RenderContext extends Bitmap {
    private final int m_scanBuffer[]; //filling with x min and x max with y axis
    byte white = (byte) 0xFF;
    // public final Vertex y_min = new Vertex(100.0f,200.0f);
    // public final Vertex y_mid = new Vertex(50.0f,400.0f);
    // public final Vertex y_max = new Vertex(200.0f,600.0f);

    public RenderContext(int width, int height)
    {
        super(width, height);//goes to bitmap.
        m_scanBuffer = new int[height*2];

    }
    public void DrawScanBuffer(int yCoord, int xMin, int XMax)
    {
        m_scanBuffer[yCoord*2] =xMin;
        m_scanBuffer[yCoord*2 + 1] =XMax;


    }
    public void drawEdges(vertex y_min,vertex y_max,boolean whichside)
    {
        float xstep = (y_max.getY()-y_min.getY())/(y_max.getX() -y_min.getX());
        float C = y_min.getY() -(y_min.getX()*xstep);
        for(int x= (int)y_min.getY();x<=(int)y_max.getY();x++)
        {

            int xMin = (int)(((float)x -C)/xstep);

            if (whichside) {//xmax
                m_scanBuffer[x*2 + 1] =xMin;
               // System.out.println("xstep is" +xstep + " xmax is"+xMin+" for y "+x);
            }
            else
            { //xmin
                m_scanBuffer[x*2] =xMin;
               // System.out.println("xstep is" +xstep+" xmin is"+xMin+" for y "+x);
            }

        }

    }
    public void drawTriangle(vertex y_min,vertex y_max,vertex y_mid)
    {
        vertex temp ;
        if (y_max.getY()<y_min.getY()) {

            temp  = y_max;
            y_max = y_min;
            y_min = temp;
        }
        if (y_max.getY()<y_mid.getY()) {
            temp  = y_max;
            y_max = y_mid;
            y_mid = temp;
        }
        if (y_mid.getY()<y_min.getY()) {
            temp  = y_mid;
            y_mid = y_min;
            y_min = temp;
        }
        if (y_min.triangleArea(y_mid, y_max)> 0) {
            drawEdges(y_min, y_max, false);
            drawEdges(y_min, y_mid, true);
            drawEdges(y_mid, y_max, true);
        } else {
            drawEdges(y_min, y_max, true);
            drawEdges(y_min, y_mid, false);
            drawEdges(y_mid, y_max, false);
        }

        fillShape((int)y_min.getY(), (int)y_max.getY());
    }
    public void fillShape(int yMin, int yMax)
    {

        for(int j =yMin;j<yMax;j++)
        {
            int xMin = m_scanBuffer[j*2];
            int xMax = m_scanBuffer[j*2 + 1];
           // System.out.println(xMin);

            for(int i=xMin;i<xMax;i++)
            {
                drawPixel(i, j, white, white, white, white);

            }
        }
    }

}