Mercurial > sdl-ios-xcode
view src/video/riscos/SDL_riscosASM.S @ 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 | 99210400e8b9 |
children |
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; ; SDL - Simple DirectMedia Layer ; Copyright (C) 1997-2009 Sam Lantinga ; ; This library is free software; you can redistribute it and/or ; modify it under the terms of the GNU Library General Public ; License as published by the Free Software Foundation; either ; version 2 of the License, or (at your option) any later version. ; ; This library is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ; Library General Public License for more details. ; ; You should have received a copy of the GNU Library General Public ; License along with this library; if not, write to the Free ; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA ; ; Sam Lantinga ; slouken@libsdl.org ; ; Assembler routines for RISC OS display ; AREA |C$$CODE| EXPORT |RISCOS_Put32| ; Display 32bpp to 32bpp, 1:1 ; ; Code provided by Adrain Lees ; ; entry a1 -> destination ; a2 = dest width in pixels ; a3 = dest line length in bytes ; a4 = dest height in scanlines ; arg5 -> source ; arg6 = byte offset from end of source line to start of next Arg5 * 10*4 Arg6 * Arg5+4 RISCOS_Put32 ROUT STMFD sp!,{a2,v1-v6,sl,fp,lr} LDR ip,[sp,#Arg5] MOV lr,a1 B ucp64lp 00 ;tail strip of 1-15 pixels LDR v1,[ip],#4 01 SUBS a2,a2,#1 STR v1,[lr],#4 LDRHI v1,[ip],#4 BHI %01 B %02 ucp64end ADDS a2,a2,#16 BNE %00 02 SUBS a4,a4,#1 ;height-- LDRHI v1,[sp,#Arg6] LDRHI a2,[sp] ;reload width BLS %03 ;move to start of next scanline ADD lr,a1,a3 ADD a1,a1,a3 ADD ip,ip,v1 ucp64lp SUBS a2,a2,#16 BLO ucp64end PLD [ip,#64] LDR v1,[ip],#4 LDR v2,[ip],#4 LDR v3,[ip],#4 LDR v4,[ip],#4 LDR v5,[ip],#4 LDR v6,[ip],#4 LDR sl,[ip],#4 LDR fp,[ip],#4 STR v1,[lr],#4 STR v2,[lr],#4 STR v3,[lr],#4 STR v4,[lr],#4 STR v5,[lr],#4 STR v6,[lr],#4 STR sl,[lr],#4 STR fp,[lr],#4 PLD [ip,#64] LDR v1,[ip],#4 LDR v2,[ip],#4 LDR v3,[ip],#4 LDR v4,[ip],#4 LDR v5,[ip],#4 LDR v6,[ip],#4 LDR sl,[ip],#4 LDR fp,[ip],#4 STR v1,[lr],#4 STR v2,[lr],#4 STR v3,[lr],#4 STR v4,[lr],#4 STR v5,[lr],#4 STR v6,[lr],#4 STR sl,[lr],#4 STR fp,[lr],#4 B ucp64lp 03 LDMFD sp!,{a2,v1-v6,sl,fp,pc}