OORingEffectEntity.m

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/*
 
OORingEffectEntity.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 "OORingEffectEntity.h"
#import "Universe.h"
#import "OOMacroOpenGL.h"
 
 
#define kRingDuration                   (2.0f)  // seconds
#define kRingAttack                     (0.4f)  // fade-up time
 
// Dimensions and growth rates per second in terms of base size.
#define kInnerRingInitialSizeFactor     (0.5f)
#define kOuterRingInitialSizeFactor     (1.25f * kInnerRingInitialSizeFactor)
#define kInnerRingGrowthRateFactor      (1.1f * kInnerRingInitialSizeFactor)
#define kOuterRingGrowthRateFactor      (1.25f * kInnerRingInitialSizeFactor)
 
// These factors produce a ring that shrinks to nothing, then expands to the size of a "normal" ring.
#define kShrinkingRingInnerGrowthFactor (-2.5)
#define kShrinkingRingOuterGrowthFactor (-2.0)
 
 
enum
{
    kCircleSegments                  = 65
};
static struct { float x, y; } sCircleVerts[kCircleSegments];  // holds vector coordinates for a unit circle
 
 
@implementation OORingEffectEntity
 
+ (void)initialize
{
    unsigned            i;
    for (i = 0; i < kCircleSegments; i++)
    {
        sCircleVerts[i].x = sinf(i * 2 * M_PI / (kCircleSegments - 1));
        sCircleVerts[i].y = cosf(i * 2 * M_PI / (kCircleSegments - 1));
    }
}
 
 
- (id) initRingFromEntity:(Entity *)sourceEntity
{
    if (sourceEntity == nil)
    {
        [self release];
        return nil;
    }
    
    if ((self = [super init]))
    {
        GLfloat baseSize = [sourceEntity collisionRadius];
        _innerRadius = baseSize * kInnerRingInitialSizeFactor;
        _outerRadius = baseSize * kOuterRingInitialSizeFactor;
        _innerGrowthRate = baseSize * kInnerRingGrowthRateFactor;
        _outerGrowthRate = baseSize * kOuterRingGrowthRateFactor;
        
        [self setPosition:[sourceEntity position]];
        [self setOrientation:[sourceEntity orientation]];
        [self setVelocity:[sourceEntity velocity]];
        
        [self setStatus:STATUS_EFFECT];
        [self setScanClass:CLASS_NO_DRAW];
        
        [self setOwner:sourceEntity];
    }
    
    return self;
}
 
 
+ (instancetype) ringFromEntity:(Entity *)sourceEntity
{
    return [[[self alloc] initRingFromEntity:sourceEntity] autorelease];
}
 
 
+ (instancetype) shrinkingRingFromEntity:(Entity *)sourceEntity
{
    OORingEffectEntity *result = [self ringFromEntity:sourceEntity];
    if (result != nil)
    {
        result->_innerGrowthRate *= kShrinkingRingInnerGrowthFactor;
        result->_outerGrowthRate *= kShrinkingRingOuterGrowthFactor;
    }
    return result;
}
 
 
- (NSString *) descriptionComponents
{
    return [NSString stringWithFormat:@"%f seconds passed of %f", _timePassed, kRingDuration];
}
 
 
- (void) update:(OOTimeDelta) delta_t
{
    [super update:delta_t];
    _timePassed += delta_t;
    
    _innerRadius += delta_t * _innerGrowthRate;
    _outerRadius += delta_t * _outerGrowthRate;
    
    if (_timePassed > kRingDuration)
    {
        [UNIVERSE removeEntity:self];
    }
}
 
 
- (void) drawImmediate:(bool)immediate translucent:(bool)translucent
{
    if (!translucent || [UNIVERSE breakPatternHide])  return;
    
    OO_ENTER_OPENGL();
    OOSetOpenGLState(OPENGL_STATE_ADDITIVE_BLENDING);
    
    GLfloat alpha = OOClamp_0_1_f((kRingDuration - _timePassed) / kRingAttack);
    
    GLfloat ex_em_hi[4]     = {0.6, 0.8, 1.0, alpha};   // pale blue
    GLfloat ex_em_lo[4]     = {0.2, 0.0, 1.0, 0.0};     // purplish-blue-black
    
    OOGLBEGIN(GL_TRIANGLE_STRIP);
        for (unsigned i = 0; i < kCircleSegments; i++)
        {
            glColor4fv(ex_em_lo);
            glVertex3f(_innerRadius * sCircleVerts[i].x, _innerRadius * sCircleVerts[i].y, 0.0f);
            glColor4fv(ex_em_hi);
            glVertex3f(_outerRadius * sCircleVerts[i].x, _outerRadius * sCircleVerts[i].y, 0.0f);
        }
    OOGLEND();
    
    OOVerifyOpenGLState();
    OOCheckOpenGLErrors(@"OOQuiriumCascadeEntity after drawing %@", self);
}
 
 
- (BOOL) isEffect
{
    return YES;
}
 
 
- (BOOL) canCollide
{
    return NO;
}
 
@end