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{ Trivial demo of some freeglut extensions, by Michalis Kamburelis,
parts based on glutdemo.pp. Public domain.
freeglut features:
- when you press escape key, program returns gracefully to main begin...end.
- we show special geometric objects: Sierpinski sponge, cylinder.
- mouse wheel up/down can be used to zoom in/out.
}
{$mode objfpc}
program FreeGlutDemo;
uses
GL, GLU, GLUT, FreeGlut;
var
T: GLFloat;
Zoom: GLFloat = -3;
procedure Display; cdecl;
const
Offset: TGLDouble3 = (0, 0, 0);
begin
glClear(GL_COLOR_BUFFER_BIT + GL_DEPTH_BUFFER_BIT);
glPushMatrix;
glTranslatef(-1, -1, Zoom);
glRotatef(T, 0, 1, 0);
glutWireCylinder(0.5, 1, 32, 8);
glPopMatrix;
glPushMatrix;
glTranslatef(-1, 1, Zoom);
glRotatef(T, 0, 1, 0);
glutSolidCylinder(0.5, 1, 32, 8);
glPopMatrix;
glPushMatrix;
glTranslatef(1, -1, Zoom);
glRotatef(T, 0, 1, 0);
glutWireSierpinskiSponge(3, @Offset, 1);
glPopMatrix;
glPushMatrix;
glTranslatef(1, 1, Zoom);
glRotatef(T, 0, 1, 0);
glutSolidSierpinskiSponge(3, @Offset, 1);
glPopMatrix;
glutSwapBuffers;
end;
procedure Timer(Value: Integer); cdecl;
begin
glutPostRedisplay;
T := T + 1.0;
glutTimerFunc(20, @Timer, 0);
end;
procedure Key(K: Byte; X, Y: Integer); cdecl;
begin
case K of
27: glutLeaveMainLoop(); // using freeglut you can exit cleanly
end;
end;
procedure Wheel(Wheel, Direction, X, Y: Integer); cdecl;
begin
if Wheel = 0 then
begin
Zoom := Zoom + Direction / 2;
glutPostRedisplay();
end;
end;
begin
glutInit(@argc, argv);
glutInitWindowSize(400, 400);
glutInitDisplayMode(GLUT_RGB or GLUT_DOUBLE or GLUT_DEPTH);
glutCreateWindow('FreeGlut demo');
glutDisplayFunc(@Display);
glutTimerFunc(20, @Timer, 0);
glutKeyboardFunc(@Key);
glutMouseWheelFunc(@Wheel);
glEnable(GL_CULL_FACE); // Enable backface culling
// Set up depth buffer
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
// Set up projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity;
gluPerspective(90, 1.3, 0.1, 100);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity;
glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_CONTINUE_EXECUTION);
WriteLn('Starting...');
glutMainLoop;
Writeln('glutMainLoop finished');
end.
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