maxrect.fp

PDE simulator on GPU.

!!FP1.0
#here compute the max element of a vector which in a 2d Texture
#HERE Texture Unit----RECT
DECLARE TexOffset ={0.0,0,0,0};

#sample the current position (i,j)
TEX R0, f[WPOS], TEX0, RECT;

#sample the (i+W/2,j)
ADD R1, f[WPOS], TexOffset.xwww;
TEX R1, R1, TEX0, RECT;
MAX R0, R0, R1;

#sample the (i,j+W/2)
ADD R1, f[WPOS], TexOffset.wxww;
TEX R1, R1, TEX0, RECT;
MAX R0, R1, R0;

#sample the (i+W/2, j+W/2)
ADD R1, f[WPOS], TexOffset.xxww;
TEX R1, R1, TEX0, RECT;

#sum 4 positions together IN 1 CHANNEL
MAX o[COLR], R1, R0;

#IF in 4 channels, need to compare RGBA components
#MAX R2, R1, R0;
#MAX R2.x, R2.x, R2.y;
#MAX R2.x, R2.x, R2.z;
#MAX o[COLR], R2.x, R2.w;

END