Metaball3

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I met this sample in GameDev forum. Finger tells how to create Metaballs on GPU with Texture. Link to Forum Thread.

Steps

  1. Create Rendering Target( 32 bit RGBA 800x600)
  2. Set Blending Mode Additive
  3. Set color alpha value 0.45
  4. Render texture on rendering target
  5. Enable Alpha Test glEnable(GL_ALPHA_TEST)
  6. Set glAphaFunc(GL_GREATER,0.5) overlapped pixel.
  7. Render result on framebuffer
  8. At last you see. It'a very nice effect

ScreenShot
Image:Metaball3a.JPG Image:Metaball3b.JPG Image:Metaball3c.JPG

Source Code 

#pragma comment (lib,"opengl32.lib")      
 
#include "../../include/SWEngine.h"
#include <gl/GL.h>
 
#pragma comment (lib,"../../lib/SWUtil.lib")    
#pragma comment (lib,"../../lib/SWTypes.lib")    
#pragma comment (lib,"../../lib/SWCore.lib")    
#pragma comment (lib,"../../lib/SWEngine.lib")    
#pragma comment (lib,"../../lib/SWGame.lib")    
#pragma comment (lib,"../../lib/SWGui.lib")    
#pragma comment (lib,"../../lib/SWServices.lib")    
 
swApplication metaballApp3;
 
typedef struct _Metaball{
	swRect target;
	int    xModifierID;
	int    imgID;
}Metaball;
 
Metaball mb1,mb2,mb3;
 
 
int windowID=-1;
int windowTexID=-1;
swRect window={0,0,800,600};
 
//-------------------------------------------------------------------------------------------
void reflectMetaballEffect(Metaball *mb){
	swGraphicsSetColor0(1,1,1,0.45);
	swGraphicsRenderImg0(mb->imgID,&mb->target);
}
 
//-------------------------------------------------------------------------------------------
void GameLoop(){ 
	swValueModifierExecute(mb1.xModifierID,0.015);	
	swValueModifierExecute(mb2.xModifierID,0.015);	
	swValueModifierExecute(mb3.xModifierID,0.015);	
 
	swGraphicsBeginScene();
 
		//Active Rendering Target
		swGraphicsSetRenderingTarget(windowID);		
		swGraphicsSetBgColor1(0,0,0,0.5);
		swGraphicsSetBlendingMode(SW_BLENDING_MODE_ADDITIVE);
		reflectMetaballEffect(&mb1);
		reflectMetaballEffect(&mb2);
		reflectMetaballEffect(&mb3);
 
		//FrameBuffer Active 
		swGraphicsSetRenderingTarget(SW_RENDERING_TARGET_DEFAULT);	
		swGraphicsSetBgColor0(0,0,0);
		swGraphicsSetBlendingMode(SW_BLENDING_MODE_NONE);
		glEnable(GL_ALPHA_TEST);
		glAlphaFunc(GL_GREATER,0.5f);
		swGraphicsSetColor0(1,1,1,1);
		swGraphicsRenderImg0(windowTexID,&window);
		glDisable(GL_ALPHA_TEST);
 
 
 
	swGraphicsEndScene();
}
 
//-------------------------------------------------------------------------------------------
int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nShowCmd)
{ 
	//Application Settings
	metaballApp3.hInstance=hInstance;
	metaballApp3.fullScreen=false;
	metaballApp3.cursor=true;
	metaballApp3.width=800;
	metaballApp3.height=600;
	metaballApp3.title="Metaball3";
	metaballApp3.path="\\rsc\\Metaball3\\";
	metaballApp3.appRun=GameLoop;
 
	//Application Execution
	swEngineInit(&metaballApp3);
 
	//Metaball1
	swRectSet(&mb1.target,200,250,256,256);
	mb1.xModifierID=swValueModifierCreate(SW_VALUE_MODIFIER_010_LOOP,&mb1.target.x,200,400,200,0);
	mb1.imgID=swGraphicsCreateImg("Ball4.tga");
 
	//Metaball2
	swRectSet(&mb2.target,400,250,236,256);
	mb2.xModifierID=swValueModifierCreate(SW_VALUE_MODIFIER_010_LOOP,&mb2.target.x,200,400,200,0);
	mb2.imgID=swGraphicsCreateImg("Blobs.tga");
 
 
	//Metaball3
	swRectSet(&mb3.target,300,150,256,256);
	mb3.xModifierID=swValueModifierCreate(SW_VALUE_MODIFIER_010_LOOP,&mb3.target.y,150,350,100,0);
	mb3.imgID=swGraphicsCreateImg("Ball3.tga");
 
 
	//RenderingTarget
	windowID=swGraphicsCreateRenderingTarget(800,600,4); //Define New RenderingTarget 
	windowTexID=swGraphicsRenderingTargetGetImgID(windowID);	
 
 
	swEngineRun();
	swEngineExit();
 
	return 0;
}
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