VP_Scatter.cg

/*
Guodong Rong

VP_Flood.cg
The vertex program for JFA

Copyright (c) 2005-2006 
School of Computing
National University of Singapore
All Rights Reserved.
*/

void main(float4 position  : POSITION,

		  out float4 oPosition        : POSITION,
		  out float3 oScatterValue	  : TEXCOORD0,

	 	  uniform float4x4 cameraModelViewProj : state.matrix.mvp,
		  uniform samplerRECT processedTex : TEXUNIT0,
		  uniform float2 size)
{
	float4 pos; 
	float2 target_pos, diff_vec;
	float4 stored_value;
	float id, dist2;
	
	pos = mul(cameraModelViewProj, position);

	stored_value = texRECT(processedTex, position.xy);
	id = int(stored_value.b);
	target_pos.y = floor(id/size.x);
	target_pos.x = id-target_pos.y*size.x;
	target_pos += 1.5;
	oPosition = mul(cameraModelViewProj, float4(target_pos, 0.0, 1.0));

	stored_value.x = stored_value.x / size.x * 2 - 1;
	stored_value.y = stored_value.y / size.y * 2 - 1;
	position.x = position.x / size.x * 2 - 1;
	position.y = position.y / size.y * 2 - 1;

	diff_vec = stored_value.xy-position.xy;
	
	dist2 = dot(diff_vec, diff_vec);

	oScatterValue = float3(diff_vec, dist2) * (4.0 / size.x / size.y);
//	oScatterValue = float3(id, size.x, floor(id/size.x));
} // main