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In order to create the additional translations, rotations and scales on the molecules, a separate procedure, makeMolecule(), was created. This function calls the molecule procedure to generate the molecule, then transforms it according to the user provided values in the transfrom section of the UI.
Also, a series of conditional tests have been added in order to inspect the values provided by the user to ensure no error producing values can be entered. If a number provided would generate a large molecule or a large number of them, the values are either corrected with a warning or the user is warned about proceeding.
The call to the procedure keyframer () at the bottom was added later to allow the molecules to be animated (explained below). |
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global proc makeMolecule(float $srad, float $crad, int $sides,
int $copies,float $tX, float $tY,
float $tZ, float $rX, float $rY,
float $rZ, float $sX, float $sY,
float $sZ, int $offT,int $offR,
int $offS, float $offH, int $animate)
{
int $n;
//int $crazy;
//for ($crazy=100; $crazy>2; $crazy--){
//$crazy can be put in place of the last number to create a
//series of shapes, the first with sides = initial value of
//$crazy, decrementing by one side until the final shape which
//has 3 sides.
float $localsrad=$srad;
float $localcrad=$crad;
int $localsides=$sides;
float $localtX=$tX; float $localtY=$tY; float $localtZ=$tZ;
float $localrX=$rX; float $localrY=$rY; float $localrZ=$rZ;
float $localsX=$sX; float $localsY=$sY; float $localsZ=$sZ;
//radius cannot be smaller than .01, sides no greater than 200.
if ($sX==0 ||$sX==0. || $sX==0.0 ) {
$localsX=1.0;
warning "ScaleX entered as zero, subtituting 1.0";
}
if ($sY==0 ||$sY==0. || $sY==0.0 ) {
$localsY=1.0;
warning "ScaleY entered as zero, subtituting 1.0";
}
if ($sZ==0 ||$sZ==0. || $sZ==0.0 ) {
$localsZ=1.0;
warning "ScaleZ entered as zero, subtituting 1.0";
}
if ($sides < 3) {
$localsides = 3;
warning "Number of Sides too small, Substituting 3";
}
if ($sides > 200) {
$localsides = 200;
warning "Number of Sides too large, Substituting 200";
}
if ($srad < .01) {
$localsrad = .01;
warning "Radius of Spheres too small, Substituting .01";
}
if($crad > $srad){
$localcrad = $srad*.66;
warning "Radii of Cylinders exceed Radii of Spheres, Substituting `print $crad`";
}
if ($copies > 150) {
string $returnVal=`confirmDialog -title "Warning! Creating more than 150 Copies."
-message "This may compromise system stability. \nAre you sure?"
-button "Proceed"
-defaultButton "Proceed"
-button "Cancel"
-cancelButton "Cancel"
-dismissString "Cancel"`;
if ($returnVal=="Cancel")
error "Operation Aborted by User.";
}
for($n = 0; $n<$copies; $n++)
{
float $up = $n * $offH;
if ($offT){
$localtX=$tX; $localtY=$tY; $localtZ=$tZ;
$localtX *= $n;
$localtY *= $n;
$localtZ *= $n;
}
if ($offR){
$localrX=$rX; $localrY=$rY; $localrZ=$rZ;
$localrX *= $n;
$localrY *= $n;
$localrZ *= $n;
}
if ($offS){
int $i;
$localsX=$sX; $localsY=$sY; $localsZ=$sZ;
for($i=0;$i<$n;$i++){
$localsX *= $sX;
$localsY *= $sY;
$localsZ *= $sZ;
}
}
string $name=molecule($localsrad, $localcrad,$localsides);
pickWalk -d up;
pickWalk -d up;
pickWalk -d up;
$up += $localtY;
xform -t $localtX $up $localtZ;
rotate $localrX $localrY $localrZ;
scale $localsX $localsY $localsZ;
if ($animate) {
keyframer($name);
}
}
}
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Our first task was to use basic MEL commands to generate the shape shown above (a "molecule"). The goal was for the shape to be one unit in size and require as few lines of code as possible to generate. The source is shown at right, and at 11 lines it became the basis for future developments by the professor and the class. The first obvious problem that needed to be addressed is that it could not create multiple molecules or molecules of additional sides due to the fact the names of objects and groups are explicitly defined and the movements are hard coded. 
