Mercurial > sdl-ios-xcode
view docs/man3/SDL_JoystickEventState.3 @ 3333:b334b4f7dfa0
[SDL] Bad math in SDL_RenderCopy
Mason Wheeler to sdl
When I tried to render an image using something other than NULL for srcrect, it got horribly distorted. I traced it down to the fact that the math in the rectangle adjustments performed just before the call to renderer->RenderCopy is written inside out. It should look like this:
if (dstrect->w != real_dstrect.w) {
int deltax = (dstrect->x - real_dstrect.x);
int deltaw = (dstrect->w - real_dstrect.w);
real_srcrect.x += (deltax * real_srcrect.w) / dstrect->w;
real_srcrect.w += (deltaw * real_srcrect.w) / dstrect->w;
}
if (dstrect->h != real_dstrect.h) {
int deltay = (dstrect->y - real_dstrect.y);
int deltah = (dstrect->h - real_dstrect.h);
real_srcrect.y += (deltay * real_srcrect.h) / dstrect->h;
real_srcrect.h += (deltah * real_srcrect.h) / dstrect->h;
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 03 Oct 2009 16:23:16 +0000 |
| parents | 546f7c1eb755 |
| children | 1238da4a7112 |
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.TH "SDL_JoystickEventState" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" .SH "NAME" SDL_JoystickEventState \- Enable/disable joystick event polling .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBint \fBSDL_JoystickEventState\fP\fR(\fBint state\fR); .SH "DESCRIPTION" .PP This function is used to enable or disable joystick event processing\&. With joystick event processing disabled you will have to update joystick states with \fI\fBSDL_JoystickUpdate\fP\fR and read the joystick information manually\&. \fBstate\fR is either \fBSDL_QUERY\fP, \fBSDL_ENABLE\fP or \fBSDL_IGNORE\fP\&. .PP .RS \fBNote: .PP Joystick event handling is prefered .RE .SH "RETURN VALUE" .PP If \fBstate\fR is \fBSDL_QUERY\fP then the current state is returned, otherwise the new processing \fBstate\fR is returned\&. .SH "SEE ALSO" .PP \fISDL Joystick Functions\fR, \fI\fBSDL_JoystickUpdate\fP\fR, \fI\fBSDL_JoyAxisEvent\fR\fR, \fI\fBSDL_JoyBallEvent\fR\fR, \fI\fBSDL_JoyButtonEvent\fR\fR, \fI\fBSDL_JoyHatEvent\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59