Hello, I am wondering how do I go about making a custom mouse cursor
work in SDL/OpenGL? As of now I am guessing disable mouse cursor, switch
to glOrtho() mode, render a fullscreen image with glRasterPos2i() to
position the mouse cursor at mouseX, mouseY?
Thanks!
Why fullscreen? And why bother with glRasterPos2i() when in ortho mode? 
All you have to do is pass the view size in pixels to glOrtho(), and handle
the “wrong way” Y axis in one way or another. In this case, it’s probably best
to just swap the 0 and height to glOrtho() to get (0, 0) in the top-left
corner, as it usually is with other APIs, SDL included.On Tuesday 02 November 2010, at 05.15.55, “Mars_999” wrote:
Hello, I am wondering how do I go about making a custom mouse cursor
work in SDL/OpenGL? As of now I am guessing disable mouse cursor, switch
to glOrtho() mode, render a fullscreen image with glRasterPos2i() to
position the mouse cursor at mouseX, mouseY?
–
//David Olofson - Consultant, Developer, Artist, Open Source Advocate
.— Games, examples, libraries, scripting, sound, music, graphics —.
| http://olofson.net http://olofsonarcade.com http://kobodeluxe.com |
’---------------------------------------------------------------------’
I figured I might as well throw a mouse cursor into Kobo II, as I’ll need one
sooner or later anyway, so here goes:
Matrix setup (origo at bottom-left, OpenGL style):
–8<-----------------------------------------------------------------
MatrixMode(PROJECTION);
LoadIdentity();
Ortho(0, screen.w, 0, screen.h, 0, 10);
MatrixMode(MODELVIEW);
LoadIdentity();
–>8-----------------------------------------------------------------
In the SDL event handling switch:
–8<-----------------------------------------------------------------
case SDL.MOUSEMOTION
{
mousex = ev.x;
mousey = screen.h - ev.y;
}
–>8-----------------------------------------------------------------
Rendering:
–8<-----------------------------------------------------------------
local cursorsize = 48;
Enable(BLEND);
BlendFunc(SRC_ALPHA, ONE);
Disable(TEXTURE_2D);
Begin(TRIANGLES);
Color(1, 1, 1, 1);
Vertex(mousex, mousey);
Color(1, 1, 0, 0);
Vertex(mousex + cursorsize * sin(PI/4),
mousey - cursorsize * sin(PI/4));
Vertex(mousex, mousey - cursorsize);
End();
–>8-----------------------------------------------------------------
(No, that’s not C. It’s EEL - but it’s still SDL and OpenGL. ;-)On Tuesday 02 November 2010, at 12.45.29, David Olofson <@David_Olofson> wrote:
On Tuesday 02 November 2010, at 05.15.55, “Mars_999” wrote:
Hello, I am wondering how do I go about making a custom mouse cursor
work in SDL/OpenGL? As of now I am guessing disable mouse cursor, switch
to glOrtho() mode, render a fullscreen image with glRasterPos2i() to
position the mouse cursor at mouseX, mouseY?Why fullscreen? And why bother with glRasterPos2i() when in ortho mode?
All you have to do is pass the view size in pixels to glOrtho(), and handle
the “wrong way” Y axis in one way or another. In this case, it’s probably
best to just swap the 0 and height to glOrtho() to get (0, 0) in the
top-left corner, as it usually is with other APIs, SDL included.
–
//David Olofson - Consultant, Developer, Artist, Open Source Advocate
.— Games, examples, libraries, scripting, sound, music, graphics —.
| http://olofson.net http://olofsonarcade.com http://kobodeluxe.com |
’---------------------------------------------------------------------’