!!ARBfp1.0

#Declarations
TEMP r0;
TEMP r1;
TEMP r2;
TEMP r3;

ATTRIB coord = fragment.texcoord[0];
ATTRIB illum = fragment.color;

PARAM scale = {2.0, 0.9, 1.8, 2.0};   
PARAM half = 0.5;
PARAM freq = {0.9, 0.9, 0.9, 0.9};  
PARAM mortarColor = {0.8, 0.8, 0.8};  
PARAM brickColor = {0.6, 0.0, 0.0};  

OUTPUT out = result.color;

#Instructions
RCP r0.x, scale.x;
RCP r0.y, scale.y;
MUL r0.xy, coord, r0;

#Apply the stagger
MUL r2.w, r0.y, half;
FRC r2.w, r2.w;
SGE r2.w, half, r2.w;
MAD r0.x, r2.w, half, r0.x;

#determine whether it is brick or mortar
FRC r0.xy, r0;
SGE r2.xy, freq, r0;
SUB r3.xy, 1.0, freq;
SGE r0.xy, r3, r0;
SUB r0.xy, r2, r0;
MUL r0.w, r0.x, r0.y;

#blend between brick and mortar
LRP r0.xyz, r0.w, brickColor, mortarColor;

#apply shading
MUL r0.xyz, r0, illum;
MAX r0.xyz, r0, 0.0;
MIN r0.xyz, r0, 1.0;

#write the result
MOV out.xyz, r0;
MOV out.w, 1.0;


END