OOSparkEntity.m

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/*
 
OOSparkEntity.m
 
 
Oolite
Copyright (C) 2004-2013 Giles C Williams and contributors
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
 
This program 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 General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
 
*/
 
#import "OOSparkEntity.h"
#import "Universe.h"
#import "PlayerEntity.h"
#import "OOColor.h"
 
 
@interface OOSparkEntity (Private)
 
- (void) performUpdate:(OOTimeDelta)delta_t;
 
@end
 
 
@implementation OOSparkEntity
 
- (id) initWithPosition:(HPVector)pos
               velocity:(Vector)vel
               duration:(OOTimeDelta)duration
                   size:(float)size
                  color:(OOColor *)color
{
    if ((self = [super initWithDiameter:size]))
    {
        [self setPosition:pos];
        [self setVelocity:vel];
        _duration = _timeRemaining = duration;
        [self setCollisionRadius:2.0];
        
        [color getRed:&_baseRGBA[0] green:&_baseRGBA[1] blue:&_baseRGBA[2] alpha:&_baseRGBA[3]];
        [self performUpdate:0]; // Handle colour mixing and such.
    }
    
    return self;
}
 
 
- (void) update:(OOTimeDelta)delta_t
{
    [super update:delta_t];
    [self performUpdate:delta_t];
}
 
 
- (void) performUpdate:(OOTimeDelta)delta_t
{
    _timeRemaining -= delta_t;
    
    float mix = OOClamp_0_1_f(_timeRemaining / _duration);
    
    // Fade towards red while fading out.
    _colorComponents[0] = mix * _baseRGBA[0] + (1.0f - mix);
    _colorComponents[1] = mix * _baseRGBA[1];
    _colorComponents[2] = mix * _baseRGBA[2];
    _colorComponents[3] = mix * _baseRGBA[3];
    
    // Disappear when gone.
    if (mix == 0)  [UNIVERSE removeEntity:self];
}
 
@end