//---------------------------------------------------------------------------
//
//	File: OpenGLPlasmaPaletteTexture.m
//
//  Abstract: Utility toolkit for handling plasma shader's color palette
//            by providing a data source to begin with
// 			 
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//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#import "OpenGLPlasmaPaletteTexture.h"

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

static const GLfloat kPi = 3.1415927f; // IEEE-754 single precision

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

@implementation OpenGLPlasmaPaletteTexture

//---------------------------------------------------------------------------

#pragma mark -
#pragma mark OpenGL Plasma Shader Texture Initializations

//---------------------------------------------------------------------------
//
// Initialize
//
//---------------------------------------------------------------------------

- (id) initPlasmaShaderPaletteWithSize:(const GLuint)thePlasmaPaletteSize
{
	self = [super initPaletteWithSize:thePlasmaPaletteSize 
						activeTexture:GL_TEXTURE1];
	
	if( self )
	{
		paletteSize = thePlasmaPaletteSize;
	} // if
	else
	{
		NSLog( @">> ERROR: OpenGL Plasma Texture Palette - Failure Allocating Plasma palette for the requested size!" );
	} // else
	
	return( self );
} // initPlasmaShaderPaletteWithSize

//---------------------------------------------------------------------------

+ (id) plasmaShaderPaletteWithSize:(const GLuint)thePlasmaPaletteSize 
{
	return  [[[OpenGLPlasmaPaletteTexture allocWithZone:[self zone]] 
			  initPlasmaShaderPaletteWithSize:thePlasmaPaletteSize] autorelease];
} // plasmaShaderPaletteWithSize

//---------------------------------------------------------------------------

#pragma mark -
#pragma mark Delete Plasma Palette

//---------------------------------------------------------------------------

- (void) dealloc 
{
    [super dealloc];
} // dealloc

//---------------------------------------------------------------------------

#pragma mark -
#pragma mark Plasma Palette Pixels

//---------------------------------------------------------------------------
//
// This is the data source for the plasma palette.
//
//---------------------------------------------------------------------------

- (GLvoid *) texturePixels:(const NSInteger)theTextureWidth 
					height:(const NSInteger)theTextureHeight 
					 depth:(const NSInteger)theTextureDepth
{
	GLuint    size    = 3 * sizeof(GLfloat) * theTextureWidth;
	GLfloat  *palette = (GLfloat *)malloc( size );
	
	if ( palette != NULL )
	{
		GLfloat   a = (GLfloat)theTextureWidth;
		GLfloat   b = 0.5f * a;
		GLfloat   c = 1.5f * a;
		GLfloat   d = 2.0f / a;
		GLfloat   x[2];
		GLfloat   n;
		GLint     i;
		GLint     j;
		
		a = 1.0f / a;
		c = 1.0f / c;
		
		for( i = 0; i < theTextureWidth; i++ )
		{
			n = (GLfloat)i;
			
			x[0] = n * kPi;
			x[1] = sinf( a * x[0] );
			
			j = 3 * i;
			
			palette[j]   = 1.0f - x[1];
			palette[j+1] = b * c * ( 1.0f + sinf( d * x[0] ) );
			palette[j+2] = x[1];
		} // for
	} // if
	
	return (GLvoid *)palette;
} // texturePixels

//---------------------------------------------------------------------------

@end

//---------------------------------------------------------------------------

//---------------------------------------------------------------------------
