{ RCSid $Id: ambpos.cal,v 2.4 2014/09/03 14:05:55 greg Exp $ } { Compute patterns for ambient position markers } odd(n) : .5*n - floor(.5*n) - .25; posangle(a) : if(-a, a + 2*PI, a) / DEGREE; { Relative hit point } rpx = Px - arg(1); rpy = Py - arg(2); rpz = Pz - arg(3); { Calculation of directional gradient pattern } ndx = arg(4); ndy = arg(5); ndz = arg(6); dgx = arg(7); dgy = arg(8); dgz = arg(9); rdx = ndy*rpz - ndz*rpy; rdy = ndz*rpx - ndx*rpz; rdz = ndx*rpy - ndy*rpx; dgrad = (rdx*dgx + rdy*dgy + rdz*dgz)/sqrt(rpx*rpx + rpy*rpy + rpz*rpz); dirfunc = bound(0, 1 + dgrad, 2); { Calculation of positional gradient pattern } pgx = arg(4); pgy = arg(5); pgz = arg(6); posfunc = bound(0, 1 + (pgx*rpx + pgy*rpy + pgz*rpz), 2); { corral flags and associated pattern } ux = arg(4); uy = arg(5); uz = arg(6); cflags = arg(7); vx = Ny*uz - Nz*uy; vy = Nz*ux - Nx*uz; vz = Nx*uy - Ny*ux; cflg(i) = if(odd(floor( cflags / 2^i )), 1, -1); corralled = cflg(floor(32/360*posangle( atan2(rpx*vx+rpy*vy+rpz*vz, rpx*ux+rpy*uy+rpz*uz) ))); { Calculation of ellipse stencil for base } usx = arg(4); usy = arg(5); usz = arg(6); vsx = arg(7); vsy = arg(8); vsz = arg(9); ellipstencil = if(1 - sq(usx*rpx + usy*rpy + usz*rpz) - sq(vsx*rpx + vsy*rpy + vsz*rpz), 1, 0);