Programming and Graphics

B Summary ofVogleFunctions 323

Rectangles and polygons

rect (x1, y1, x2, y2) Draw a rectangle

polyfill (onoff) Set the polygon fill flag

polyhatch (onoff) Set the polygon hatch flag

hatchang (angle) Set the angle of the hatch lines

hatchpitch (pitch) Set the distance between hatch lines

poly2 (n, points) Construct an (x, y) polygon

from an array of point

poly (n, points) Construct a polygon from an array of points

makepoly () Open a polygon constructed by a series

of move-draws and closed by closepoly

closepoly () Terminate a polygon opened by makepoly

backface (onoff) Turn on culling of backfacing polygons

backfacedir (clockwise) Set backfacing direction to clockwise

or anti-clockwise

Patches

patchbasis (tbasis, ubasis) Define the t and u basis matrices of a patch

patchprecision (tseg, useg) Set minimum number of line segments

making up curves in a patch

patchcurves (nt, nu) Set the number of curves making up a patch

rpatch (gx, gy, gz, gw) Draw a rational patch in the current basis,

according to the geometry matrices

gx, gy, gz, and gw

patch (gx, gy, gz) Draw a patch in the current basis

according to the geometry matrices

gx, gy, and gz

Objects

makeobj (n) Commence the object number n

closeobj () Close the current object

int genobj () Get a unique object identifier

int getopenobj () Get the number of the current object

callobj (n) Draw object number n

int isobj (n) Return non-zero if an object numbered n

has been defined

delobj (n) Delete the object number n

loadobj (n, filename) Load the object number n

in the file filename

saveobj (n, filename) Save the object number n into file filename;

doesnotsave objects called inside object n