Mercurial > sdl-ios-xcode
annotate Xcode-iPhoneOS/Demos/src/common.c @ 5053:b5b42be9333c
Fixed bug #1026
Vittorio Giovara 2010-07-16 19:09:28 PDT
i was reading SDL_renderer_gles and i noticed that every time we there
is some gl call the gl state is modified with a couple of
glEnableClientState()/glDisableClientState.
While this is completely fine for desktops systems, this is a major
performace kill on mobile devices, right where opengles is
implemented.
Normal practice in this case is to update the glstate once, keep it
always the same and disable/enable other states only in very special
occasions.
On the web there's plenty of documentation (on the top of my head
http://developer.apple.com/iphone/library/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/Performance/Performance.html#//apple_ref/doc/uid/TP40008793-CH105-SW5
) and i personally tried this.
I modified my code and got a 10 fps boost, then modified SDL_render_gles and
shifted from 40 fps to 50 fps alone -- considering that i started from ~30fps i
got an 80% performance increase with this technique.
I have attached a dif of my changes, hope that it will be included in
mainstream.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Wed, 19 Jan 2011 23:56:16 -0800 |
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1 /* |
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2 * common.c |
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3 * written by Holmes Futrell |
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4 * use however you want |
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5 */ |
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6 |
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7 #include "common.h" |
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8 #include "SDL.h" |
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9 #include <stdlib.h> |
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10 |
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11 /* |
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12 Produces a random int x, min <= x <= max |
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13 following a uniform distribution |
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14 */ |
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15 int |
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16 randomInt(int min, int max) |
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17 { |
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18 return min + rand() % (max - min + 1); |
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19 } |
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20 |
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21 /* |
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22 Produces a random float x, min <= x <= max |
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23 following a uniform distribution |
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24 */ |
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25 float |
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26 randomFloat(float min, float max) |
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27 { |
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28 return rand() / (float) RAND_MAX *(max - min) + min; |
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29 } |
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30 |
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31 void |
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32 fatalError(const char *string) |
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33 { |
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34 printf("%s: %s\n", string, SDL_GetError()); |
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35 exit(1); |
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36 } |