DrawTrapezium

void DrawImage( )
{
    POLYGON polyTempP, polyTempQ, polyTempQT;   // Temporary polygons for copying transformed, projected / clipped
                                                // versions of scene polys before drawing them.
    int iCurrentPoly;                           // Current polygon in process

    if ( m_iNumOfPolys <= 0 )
        //DrawSquare(Default_Colour );      // This draws the square you see, replace with Trapezium, and later Polygon
     DrawTrapezium(Default_Colour, 50 + m_iMoveX, m_iMoveX, 0.5, -0.5, 200, 120 + m_iMoveY, m_iMoveY);
    else
        m_iOurFrameCount++; // Increment frame counter if we have a polygon to draw

    for ( iCurrentPoly = 0; iCurrentPoly < m_iNumOfPolys; iCurrentPoly++ )  // for each polygon
    {
        if ( iFaceSelection > m_iNumOfPolys )
            iFaceSelection = m_iNumOfPolys;    //Keep debug selector in range


        if ( iFaceSelection && ( iCurrentPoly + 1 ) != iFaceSelection)
            continue; // Reject unselected polygons if debug selection active.


        polyTempP = polylist[iCurrentPoly];             //copy static data into temp poly structure

        // Copy each vertex in polygon, add displacement to allow shift
        for (int i = 0; i < polylist[iCurrentPoly].nv; i++)
        {
            polyTempP.vert[i].x = polylist[iCurrentPoly].vert[i].x + m_iMoveX;
            polyTempP.vert[i].y = polylist[iCurrentPoly].vert[i].y + m_iMoveY;
        }

        if ( bDebug )
            fprintf( debugfile, " number of vertices: %d\n", polyTempP.nv);   // print number of vertices

        fflush( debugfile );

        if ( bDebug )   // Print out current poly specs if debug active
        {
            for (int i = 0; i < polyTempP.nv; i++)
            {
                fprintf( debugfile, "before clipping Polygon %d, Vertex %d values: %7.2f, %7.2f, %11.6f\n",
                         iCurrentPoly, i, polyTempP.vert[i].x, polyTempP.vert[i].y, polyTempP.vert[i].z );
            }
            fflush( debugfile );

        }
        // The section below calls clipping and polygon draw routines, commented out to allow the
        // program to work without them. You may re-instate once you have appropriate routines,
        // or replace with your own code.
        /*
        ClipPolyXHigh( &polyTempP, &polyTempQT, WINDOWWIDTH );  // Clip against upper x boundary
        ClipPolyYHigh( &polyTempQT, &polyTempQ, WINDOWHEIGHT ); // Clip against upper y boundary (bottom of screen)
        ClipPolyXLow( &polyTempQ, &polyTempQT, 0);              // Clip against lower x boundary
        ClipPolyYLow( &polyTempQT, &polyTempQ, 0);              // Clip against lower y boundary (bottom of screen)

        if ( bDebug )   // Print out current poly specs if debug active
        {
            for ( int i = 0; i < polyTempQ.nv; i++ )
                fprintf( debugfile, "after clipping Polygon %d Vertex %d values:y %7.2f  %7.2f %11.6f\n",
                         iCurrentPoly, i, polyTempQ.vert[i].x, polyTempQ.vert[i].y, polyTempQ.vert[i].z );

            fflush(debugfile);
        }

        DrawPolygon( &polyTempQ );  // Call the drawing routine
        */
    }
    if ( m_iNumOfPolys > 0 )
        bDebug = false; // Switch debug off after first run - switch on again via keyboard control if needed


}

//-----------------------------------------------------------------------------
// Name: DrawSquare
// Desc: Draw a sqaure
//-----------------------------------------------------------------------------
//void DrawSquare(COLOUR c )
void DrawTrapezium( COLOUR c , float x_end, float x_start, float slope_right, float slope_left, int m_iMoveX, float y_end, float y_start)
{
    //x_end = 50+m_iMoveX;
    //float x_end = 50 + m_iMoveX; //right slope
    //float x_start = m_iMoveX; //left slope
    //float slope_right =0.5;
    //float slope_left =-0.5;
    //int m_iMoveX = 200; //task 9
    //
    //float y_end = 120+ m_iMoveY;
    //float y_start = m_iMoveY;

    //Note no protection to keep in screen bounds...
    for ( int j = y_start; j < y_end; j++)
    //for ( int i = m_iMoveX; i < 50 + m_iMoveX; i++)
    {
        x_end = x_end + slope_right; //this line is so the float 'slope_right' can easily be changed to make the slope different
        x_start = x_start + slope_left;
        for ( int i =x_start; i < x_end; i++)
        //for( int j = m_iMoveY; j < 50 + m_iMoveY; j++)
        {

            Plotpix( i, j, c.r, c.g, c.b );
        }
    }
}