ParticleEmitter.h

//
//  ParticleEmitter.h
//  ParticleEmitterDemo
//
// Copyright (c) 2010 71Squared
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#import "Global.h"

@class Texture2D;

// Particle type
enum kParticleTypes {
	kParticleTypeGravity,
	kParticleTypeRadial
};

// Structure that holds the location and size for each point sprite
typedef struct {
	GLfloat x;
	GLfloat y;
    GLfloat s;
    GLfloat t;
	Color4f color;
} PointSprite;

typedef struct {
    Vector2f vertex;
    Vector2f texture;
    Color4f color;
} TexturedColoredVertex;

typedef struct {
    TexturedColoredVertex bl;
    TexturedColoredVertex br;
    TexturedColoredVertex tl;
    TexturedColoredVertex tr;
} ParticleQuad;

// Structure used to hold particle specific information
typedef struct {
	Vector2f position;
	Vector2f direction;
    Vector2f startPos;
	Color4f color;
	Color4f deltaColor;
    GLfloat rotation;
    GLfloat rotationDelta;
    GLfloat radialAcceleration;
    GLfloat tangentialAcceleration;
	GLfloat radius;
	GLfloat radiusDelta;
	GLfloat angle;
	GLfloat degreesPerSecond;
	GLfloat particleSize;
	GLfloat particleSizeDelta;
	GLfloat timeToLive;
} Particle;

#define MAXIMUM_UPDATE_RATE 90.0f	// The maximum number of updates that occur per frame

// The particleEmitter allows you to define parameters that are used when generating particles.
// These particles are OpenGL particle sprites that based on the parameters provided each have
// their own characteristics such as speed, lifespan, start and end colors etc.  Using these
// particle emitters allows you to create organic looking effects such as smoke, fire and 
// explosions.
//
// The design for this particle emitter was influenced by the point sprite particle system
// used in the Cocos2D game engine
//
@interface ParticleEmitter : NSObject {

	/////////////////// Particle iVars
    int emitterType;
	Texture2D *texture;												
	Vector2f sourcePosition, sourcePositionVariance;			
	GLfloat angle, angleVariance;								
	GLfloat speed, speedVariance;	
    GLfloat radialAcceleration, tangentialAcceleration;
    GLfloat radialAccelVariance, tangentialAccelVariance;
	Vector2f gravity;	
	GLfloat particleLifespan, particleLifespanVariance;			
	Color4f startColor, startColorVariance;						
	Color4f finishColor, finishColorVariance;
	GLfloat startParticleSize, startParticleSizeVariance;
	GLfloat finishParticleSize, finishParticleSizeVariance;
	GLuint maxParticles;
	GLint particleCount;
	GLfloat emissionRate;
	GLfloat emitCounter;	
	GLfloat elapsedTime;
	GLfloat duration;
    GLfloat rotationStart, rotationStartVariance;
    GLfloat rotationEnd, rotationEndVariance;

	int blendFuncSource, blendFuncDestination;

	//////////////////// Particle ivars only used when a maxRadius value is provided.  These values are used for
	//////////////////// the special purpose of creating the spinning portal emitter
	GLfloat maxRadius;						// Max radius at which particles are drawn when rotating
	GLfloat maxRadiusVariance;				// Variance of the maxRadius
	GLfloat radiusSpeed;					// The speed at which a particle moves from maxRadius to minRadius
	GLfloat minRadius;						// Radius from source below which a particle dies
	GLfloat minRadiusVariance;				// Variance of the minRadius
	GLfloat rotatePerSecond;				// Numeber of degress to rotate a particle around the source pos per second
	GLfloat rotatePerSecondVariance;		// Variance in degrees for rotatePerSecond

	//////////////////// Particle Emitter iVars
	BOOL active;
	BOOL useTexture;
	GLint particleIndex;		// Stores the number of particles that are going to be rendered
    GLint vertexIndex;         // Stores the index of the vertices being used for each particle

	
	///////////////////// Render
	GLuint verticesID;			// Holds the buffer name of the VBO that stores the color and vertices info for the particles
    GLuint vertexObjectID;
	Particle *particles;		// Array of particles that hold the particle emitters particle details
	ParticleQuad *quads;        // Array holding quad information for each particle;
    GLushort *indices;          // Array holding an index reference into an array of quads for rendering
}

@property(nonatomic, assign) Vector2f sourcePosition;
@property(nonatomic, assign) GLint particleCount;
@property(nonatomic, assign) BOOL active;
@property(nonatomic, assign) GLfloat duration;

// Initialises a particle emitter using configuration read from a file
- (id)initParticleEmitterWithFile:(NSString*)aFileName;

// Renders the particles for this emitter to the screen
- (void)renderParticles;

// Updates all particles in the particle emitter
- (void)updateWithDelta:(GLfloat)aDelta;

// Stops the particle emitter
- (void)stopParticleEmitter;

@end