www.pudn.com > GPU-KLT-1.0.zip > klt_detector_pass2.cg

/*
Copyright (c) 2008 University of North Carolina at Chapel Hill

This file is part of GPU-KLT.

GPU-KLT is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option) any
later version.

GPU-KLT is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
details.

You should have received a copy of the GNU Lesser General Public License along
with GPU-KLT. If not, see .
*/

float sqr(float x) { return x*x; }

void main(uniform sampler2D src_tex : TEXUNIT0,
          float4 st0 : TEXCOORD0,
          float4 st1 : TEXCOORD1,
          float4 st2 : TEXCOORD2,
          float4 st3 : TEXCOORD3,
          uniform float minCornerness,
          uniform float4 validRegion,
          out float4 color : COLOR)
{
   float3 abc = float3(0);

   abc += tex2D(src_tex, st0.xy).xyz;
   abc += tex2D(src_tex, st0.zw).xyz;
   abc += tex2D(src_tex, st1.xy).xyz;
   abc += tex2D(src_tex, st1.zw).xyz;
   abc += tex2D(src_tex, st2.xy).xyz;
   abc += tex2D(src_tex, st2.zw).xyz;
   abc += tex2D(src_tex, st3.xy).xyz;

   float a = abc.x;
   float b = abc.y;
   float c = abc.z;

   float cornerness = 0.5f*(a+c - sqrt(sqr(a-c) + 4*sqr(b)));
   //cornerness = (cornerness >= minCornerness) ? cornerness : 0.0f;
   cornerness = max(cornerness - minCornerness, float4(0));

   float2 st = st1.zw;
   cornerness = (all(st >= validRegion.xy) && all(st <= validRegion.zw)) ? cornerness : 0.0f;

   color = unpack_4ubyte(cornerness);
}