Mercurial > sdl-ios-xcode
view src/video/dummy/SDL_nullvideo.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> |
---|---|
date | Wed, 19 Jan 2011 23:56:16 -0800 |
parents | f7b03b6838cb |
children | fb424691cfc7 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2010 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* Dummy SDL video driver implementation; this is just enough to make an * SDL-based application THINK it's got a working video driver, for * applications that call SDL_Init(SDL_INIT_VIDEO) when they don't need it, * and also for use as a collection of stubs when porting SDL to a new * platform for which you haven't yet written a valid video driver. * * This is also a great way to determine bottlenecks: if you think that SDL * is a performance problem for a given platform, enable this driver, and * then see if your application runs faster without video overhead. * * Initial work by Ryan C. Gordon (icculus@icculus.org). A good portion * of this was cut-and-pasted from Stephane Peter's work in the AAlib * SDL video driver. Renamed to "DUMMY" by Sam Lantinga. */ #include "SDL_video.h" #include "SDL_mouse.h" #include "../SDL_sysvideo.h" #include "../SDL_pixels_c.h" #include "../../events/SDL_events_c.h" #include "SDL_nullvideo.h" #include "SDL_nullevents_c.h" #include "SDL_nullrender_c.h" #define DUMMYVID_DRIVER_NAME "dummy" /* Initialization/Query functions */ static int DUMMY_VideoInit(_THIS); static int DUMMY_SetDisplayMode(_THIS, SDL_VideoDisplay * display, SDL_DisplayMode * mode); static void DUMMY_VideoQuit(_THIS); /* DUMMY driver bootstrap functions */ static int DUMMY_Available(void) { const char *envr = SDL_getenv("SDL_VIDEODRIVER"); if ((envr) && (SDL_strcmp(envr, DUMMYVID_DRIVER_NAME) == 0)) { return (1); } return (0); } static void DUMMY_DeleteDevice(SDL_VideoDevice * device) { SDL_free(device); } static SDL_VideoDevice * DUMMY_CreateDevice(int devindex) { SDL_VideoDevice *device; /* Initialize all variables that we clean on shutdown */ device = (SDL_VideoDevice *) SDL_calloc(1, sizeof(SDL_VideoDevice)); if (!device) { SDL_OutOfMemory(); if (device) { SDL_free(device); } return (0); } /* Set the function pointers */ device->VideoInit = DUMMY_VideoInit; device->VideoQuit = DUMMY_VideoQuit; device->SetDisplayMode = DUMMY_SetDisplayMode; device->PumpEvents = DUMMY_PumpEvents; device->free = DUMMY_DeleteDevice; return device; } VideoBootStrap DUMMY_bootstrap = { DUMMYVID_DRIVER_NAME, "SDL dummy video driver", DUMMY_Available, DUMMY_CreateDevice }; int DUMMY_VideoInit(_THIS) { SDL_DisplayMode mode; /* Use a fake 32-bpp desktop mode */ mode.format = SDL_PIXELFORMAT_RGB888; mode.w = 1024; mode.h = 768; mode.refresh_rate = 0; mode.driverdata = NULL; if (SDL_AddBasicVideoDisplay(&mode) < 0) { return -1; } SDL_AddRenderDriver(&_this->displays[0], &SDL_DUMMY_RenderDriver); SDL_zero(mode); SDL_AddDisplayMode(&_this->displays[0], &mode); /* We're done! */ return 0; } static int DUMMY_SetDisplayMode(_THIS, SDL_VideoDisplay * display, SDL_DisplayMode * mode) { return 0; } void DUMMY_VideoQuit(_THIS) { } /* vi: set ts=4 sw=4 expandtab: */