cohensutherland's Introduction

CohenSutherland

Cohen Sutherland line clipping algorithm in Pascal ( Delphi )

This is a port of C code from Wikipedia to Delphi:

http://en.wikipedia.org/wiki/Cohen%E2%80%93Sutherland

The test application (VCL) can be used either by typing the line segment end-point coordinates or by clicking two points on the form.

Algorithm Usage

1- Add unit to uses

uses                           
   CohenSutherlandClipping;

2- Set clipping rectangle

var xmin, ymin, xmax, ymax:Double;
begin
  xmin := 10;   ymin := 10;  xmax := 100;  ymax := 200; 
  CohenSutherland_SetClippingRect(xmin, ymin, xmax, ymax ); 
  ...

3- Test line clipping

var x0,y0,x1,y1:Double;
begin
  x0 := 0;   y0 := 0;  x1 := 300;  y1 := 400;       // set line segment end points
  if CohenSutherland_LineVisible(x0,y0,x1,y1) then  // if line is visible, x0,y0,x1,y1 returns.. 
     begin                                          // ..clipped line end points
       Canvas.MoveTo( Trunc(x0),  Trunc(y0) );      // draw line segment ( VCL flavour ) 
       Canvas.LineTo( Trunc(x1),  Trunc(y1) );
     end;

App tested with Delphi 7 and D11.1

Originally I did this port to use with graphics32, because the standard "Safe" clipping TBitmap32.LineToAS() didn't work for large x, y ( this was for 2012, don't know if it works now ). Anyway, this algorithm can be used with any graphics (ex: FMX)

Om-Oct/22

#Delphi #Graphics #Cohen-Sutherland

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