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SpriteAction_AlphaPulse.cpp

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//*** SpriteAction_AlphaPulse.cpp ***
 
#include "SpriteAction_AlphaPulse.h"
#include "ColorHelper.h"
#include "Sprite.h"
#include "StandardLibrary.h"


//*** Constructor ***

SpriteAction_AlphaPulse::SpriteAction_AlphaPulse(float speed):
   speed_(speed),
   currentSource_(0),
   currentTarget_(0)
   {
   if (speed_<=0)
      {
      speed_=FLOAT_EPSILON;
      }
   }


//*** Setup ***

void SpriteAction_AlphaPulse::Setup(SpriteController* controller, Sprite* sprite)
   {
   unsigned char sourceAlpha=sprite->GetAlpha();
   currentSource_=((float)sourceAlpha)/255.0f;
   currentTarget_=0.0f;
   }


//*** Update ***

void SpriteAction_AlphaPulse::Update(SpriteController* controller, Sprite* sprite, float deltaTime)
   {
   if (currentTarget_<currentSource_)
      {
      currentSource_-=deltaTime*speed_;
      if (currentSource_<=currentTarget_)
         {
         currentSource_=0.0f;
         currentTarget_=1.0f;
         }
      }
   else
      {
      currentSource_+=deltaTime*speed_;
      if (currentSource_>=currentTarget_)
         {
         currentSource_=1.0f;
         currentTarget_=0.0f;
         }
      }
   int alpha=Clamp((int)(currentSource_*255.0f),1,255);
   
   sprite->SetAlpha((char)alpha);
   }

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