Hi,
In my code I experience a problem with drawing stippled lines with
OpenGL. In the following example no line is drawn, but when I change
glVertex2f(40, 480); to glVertex2f(640, 480); there is a stippled line
drawn. On the other hand, when I comment glEnable(GL_LINE_STIPPLE); then
a solid line is draw in both cases.
Am I making some subtle mistake in commands, or is there a bug here?
I'm using: 2.4.0-2 [2010/03/06] for i386
Regards, Darius
program gl_test;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX} {$IFDEF UseCThreads}
cthreads,
{$ENDIF} {$ENDIF}
GL, GLut;
procedure DisplayFunc; cdecl;
begin
glMatrixMode(GL_PROJECTION);
glLoadIdentity;
glOrtho(0, 640, 480, 0, 0, 1);
glMatrixMode(GL_MODELVIEW);
glDisable(GL_DEPTH_TEST);
glShadeModel(GL_FLAT);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glClear(GL_COLOR_BUFFER_BIT);
glLineWidth(5);
glEnable(GL_LINE_STIPPLE); //comment line
glLineStipple(1, $0101);
glBegin(GL_LINES);
glColor3f(1, 0, 0);
glVertex2f(0, 0);
glVertex2f(40, 480); //change to glVertex2f(640, 480);
glEnd;
glDisable(GL_LINE_STIPPLE);
glutSwapBuffers;
end;
begin
glutInit(@argc, argv);
glutInitDisplayMode(GLUT_DOUBLE or GLUT_RGBA);
glutInitWindowSize(640, 480);
glutInitWindowPosition(100, 100);
glutCreateWindow('OpenGL test');
glutDisplayFunc(@DisplayFunc);
glClearColor(0, 0, 0, 1);
glutMainLoop;
end.
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