view src/joystick/iphoneos/SDLUIAccelerationDelegate.m @ 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 99210400e8b9
children b530ef003506
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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 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
 */

#import "SDLUIAccelerationDelegate.h"
/* needed for SDL_IPHONE_MAX_GFORCE macro */
#import "../../../include/SDL_config_iphoneos.h"

static SDLUIAccelerationDelegate *sharedDelegate=nil;

@implementation SDLUIAccelerationDelegate

/*
	Returns a shared instance of the SDLUIAccelerationDelegate, creating the shared delegate if it doesn't exist yet.
*/
+(SDLUIAccelerationDelegate *)sharedDelegate {
	if (sharedDelegate == nil) {
		sharedDelegate = [[SDLUIAccelerationDelegate alloc] init];
	}
	return sharedDelegate;
}
/*
	UIAccelerometerDelegate delegate method.  Invoked by the UIAccelerometer instance when it has new data for us.
	We just take the data and mark that we have new data available so that the joystick system will pump it to the
	events system when SDL_SYS_JoystickUpdate is called.
*/	
-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
		
	x = acceleration.x;
	y = acceleration.y;
	z = acceleration.z;
	
	hasNewData = YES;	
}
/* 
	getLastOrientation -- put last obtained accelerometer data into Sint16 array
 
	Called from the joystick system when it needs the accelerometer data.
	Function grabs the last data sent to the accelerometer and converts it 
	from floating point to Sint16, which is what the joystick system expects.
 
	To do the conversion, the data is first clamped onto the interval
	[-SDL_IPHONE_MAX_G_FORCE, SDL_IPHONE_MAX_G_FORCE], then the data is multiplied
	by MAX_SINT16 so that it is mapped to the full range of an Sint16.
 
	You can customize the clamped range of this function by modifying the 
	SDL_IPHONE_MAX_GFORCE macro in SDL_config_iphoneos.h.
 
	Once converted to Sint16, the accelerometer data no longer has coherent units.
	You can convert the data back to units of g-force by multiplying it 
	in your application's code by SDL_IPHONE_MAX_GFORCE / 0x7FFF.
 */
-(void)getLastOrientation:(Sint16 *)data {

	#define MAX_SINT16 0x7FFF	

	/* clamp the data */
	if (x > SDL_IPHONE_MAX_GFORCE) x = SDL_IPHONE_MAX_GFORCE;
	else if (x < -SDL_IPHONE_MAX_GFORCE) x = -SDL_IPHONE_MAX_GFORCE;
	if (y > SDL_IPHONE_MAX_GFORCE) y = SDL_IPHONE_MAX_GFORCE;
	else if (y < -SDL_IPHONE_MAX_GFORCE) y = -SDL_IPHONE_MAX_GFORCE;
	if (z > SDL_IPHONE_MAX_GFORCE) z = SDL_IPHONE_MAX_GFORCE;
	else if (z < -SDL_IPHONE_MAX_GFORCE) z = -SDL_IPHONE_MAX_GFORCE;
	
	/* pass in data mapped to range of SInt16 */
	data[0] = (x / SDL_IPHONE_MAX_GFORCE) * MAX_SINT16;
	data[1] = (y / SDL_IPHONE_MAX_GFORCE) * MAX_SINT16;
	data[2] = (z / SDL_IPHONE_MAX_GFORCE) * MAX_SINT16;

}

/*
	Initialize SDLUIAccelerationDelegate.  Since we don't have any data yet,
	just set our last received data to zero, and indicate we don't have any;
*/
-(id)init {
	self = [super init];
	x = y = z = 0.0;
	hasNewData = NO;
	return self;
}

-(void)dealloc {
	sharedDelegate = nil;
	[self shutdown];
	[super dealloc];
}

/*
	Lets our delegate start receiving accelerometer updates.
*/
-(void)startup {
	[UIAccelerometer sharedAccelerometer].delegate = self;
	isRunning = YES;
}
/*
	Stops our delegate from receiving accelerometer updates.
*/
-(void)shutdown {
	if ([UIAccelerometer sharedAccelerometer].delegate == self) {
		[UIAccelerometer sharedAccelerometer].delegate = nil;
	}
	isRunning = NO;
}
/*
	Our we currently receiving accelerometer updates?
*/
-(BOOL)isRunning {
	return isRunning;
}
/*
	Do we have any data that hasn't been pumped into SDL's event system?
*/
-(BOOL)hasNewData {
	return hasNewData;
}
/*
	When the joystick system grabs the new data, it sets this to NO.
*/
-(void)setHasNewData:(BOOL)value {
	hasNewData = value;
}

@end