proc main {} {
initVars
buildUI
animate}
proc animate {} {
# --- crank it as fast as we can...
while {$::emitter(alive)} {
nextFrame
update
}
exit}
proc initVars {} {
# --- Particle Emitter...
set ::emitter(alive) 1 ; # still running?
set ::emitter(pos.x) 300 ; # x position of emitter
set ::emitter(pos.y) 370 ; # y position of emitter
set ::emitter(pos.z) 0 ; # z position of emitter
set ::emitter(yaw) [degreeToRad 0] ; # initial yaw angle
set ::emitter(yawVar) [degreeToRad 360] ; # random variation range on yaw
set ::emitter(pitch) [degreeToRad -90] ; # initial pitch (up)
set ::emitter(pitchVar) [degreeToRad 40] ; # random variation range
set ::emitter(speed) 12 ; # particle speed
set ::emitter(speedVar) 2 ; # random variation range
set ::emitter(totalParticles) 50 ; # total particles in system
set ::emitter(particleCount) 0 ; # current particle count
set ::emitter(emitsPerFrame) 5 ; # number of particles/frame
set ::emitter(emitVar) 2 ; # random variation range
set ::emitter(life) 60 ; # particle life (frames)
set ::emitter(lifeVar) 15 ; # random variation
set ::emitter(startColor.r) 150 ; # start color (red component)
set ::emitter(startColor.g) 150 ; # start color (green component)
set ::emitter(startColor.b) 200 ; # start color (blue component)
set ::emitter(startColorVar.r) 25 ; # random variation - red
set ::emitter(startColorVar.g) 25 ; # random variation - green
set ::emitter(startColorVar.b) 25 ; # random variation - blue
set ::emitter(endColor.r) 0 ; # end color (red component)
set ::emitter(endColor.g) 0 ; # end color (green component)
set ::emitter(endColor.b) 200 ; # end color (blue component)
set ::emitter(endColorVar.r) 25 ; # random variation - red
set ::emitter(endColorVar.g) 25 ; # random variation - green
set ::emitter(endColorVar.b) 50 ; # random variation - blue
set ::emitter(force.x) 0.0 ; # x force factor (wind)
set ::emitter(force.y) 0.3 ; # y force factor (gravity)
set ::emitter(force.z) 0.0 ; # z force factor (?)}
proc nextFrame {} {
# --- update all living particles
foreach me [.c1 find withtag "alive"] {
updateParticle $me
}
# --- Add up to "emitsPerFrame" more particles to the scene without
# exceeding "totalParticles"
for {set i 1} {$i <= $::emitter(emitsPerFrame)} {incr i} {
if {![addNewParticle]} {
break
}
}}
proc addNewParticle {} {
# --- if we've reached our population cap, just return
if {$::emitter(particleCount) >= $::emitter(totalParticles)} {
return 0
} else {
# --- throw another particle on the pile
incr ::emitter(particleCount)
# --- see if we can recycle any dead particles
set me [lindex [.c1 find withtag "dead"] 0]
if {[string length $me]} {
.c1 itemconfigure $me -tag "alive"
} else {
set me [.c1 create line -tag "alive"]
}
# --- starting particle position (delta from the emitter)
set ::particle($me,pos.x) 0
set ::particle($me,pos.y) 0
set ::particle($me,pos.z) 0
set ::particle($me,prevPos.x) 0
set ::particle($me,prevPos.y) 0
set ::particle($me,prevPos.z) 0
# --- calculate the starting direction vector
set yaw [expr {$::emitter(yaw) + ($::emitter(yawVar) * [randomNum])}]
set pitch [expr {$::emitter(pitch) + ($::emitter(pitchVar) * [randomNum])}]
# --- determine vector information
set vectorInfo [rotationToDirection $pitch $yaw]
set x [lindex $vectorInfo 0]
set y [lindex $vectorInfo 1]
set z [lindex $vectorInfo 2]
# --- account for the speed factor
set speed [expr {$::emitter(speed) + ($::emitter(speedVar) * [randomNum])}]
set x [expr {$x * $speed}]
set y [expr {$y * $speed}]
set z [expr {$z * $speed}]
# --- we are done with these, so store them with the particle
set ::particle($me,dir.x) $x
set ::particle($me,dir.y) $y
set ::particle($me,dir.z) $z
# --- calculate the colors for this particle
set start_r [expr {$::emitter(startColor.r) + \
($::emitter(startColorVar.r) * [randomNum])}]
set start_g [expr {$::emitter(startColor.g) + \
($::emitter(startColorVar.g) * [randomNum])}]
set start_b [expr {$::emitter(startColor.b) + \
($::emitter(startColorVar.b) * [randomNum])}]
set end_r [expr {$::emitter(endColor.r) + \
($::emitter(endColorVar.r) * [randomNum])}]
set end_g [expr {$::emitter(endColor.g) + \
($::emitter(endColorVar.g) * [randomNum])}]
set end_b [expr {$::emitter(endColor.b) + \
($::emitter(endColorVar.b) * [randomNum])}]
set ::particle($me,color.r) $start_r
set ::particle($me,color.g) $start_g
set ::particle($me,color.b) $start_b
# --- calculate the lifespan of this particle
# we know *exactly* how long it will live, even before it's born...
set life [expr {$::emitter(life) + int($::emitter(lifeVar) * [randomNum])}]
set ::particle($me,life) $life
# --- calculate the color delta using the lifespan of this particle
set ::particle($me,deltaColor.r) [expr {($end_r - $start_r) / $life}]
set ::particle($me,deltaColor.g) [expr {($end_g - $start_g) / $life}]
set ::particle($me,deltaColor.b) [expr {($end_b - $start_b) / $life}]
# --- A new particle is born - it's a beautiful thing...
return 1
}}
proc updateParticle {me} {
# --- if this particle has died, prepare for it for resurrection...
if {$::particle($me,life) <= 0} {
incr ::emitter(particleCount) -1
.c1 itemconfigure $me -tag "dead"
.c1 coords $me -10 -10 -10 -10
return 0
} else {
# --- save it's old position as the next start coord
set ::particle($me,prevPos.x) $::particle($me,pos.x)
set ::particle($me,prevPos.y) $::particle($me,pos.y)
set ::particle($me,prevPos.z) $::particle($me,pos.z)
# --- update the new end coordinates by the particles motion vectors
set ::particle($me,pos.x) [expr {$::particle($me,pos.x) + \
$::particle($me,dir.x)}]
set ::particle($me,pos.y) [expr {$::particle($me,pos.y) + \
$::particle($me,dir.y)}]
set ::particle($me,pos.z) [expr {$::particle($me,pos.z) + \
$::particle($me,dir.z)}]
# --- apply global forces to the particle
set ::particle($me,dir.x) [expr {$::particle($me,dir.x) + \
$::emitter(force.x)}]
set ::particle($me,dir.y) [expr {$::particle($me,dir.y) + \
$::emitter(force.y)}]
set ::particle($me,dir.z) [expr {$::particle($me,dir.z) + \
$::emitter(force.z)}]
# --- update the particle color
set ::particle($me,color.r) [expr {$::particle($me,color.r) + \
$::particle($me,deltaColor.r)}]
set ::particle($me,color.g) [expr {$::particle($me,color.g) + \
$::particle($me,deltaColor.g)}]
set ::particle($me,color.b) [expr {$::particle($me,color.b) + \
$::particle($me,deltaColor.b)}]
# --- Age the particle...
# In the immortal words of Pink Floyd...
# "The sun is the same in a relative way, but you're older"
# "Shorter of breath and one day closer to death"
incr ::particle($me,life) -1
set x_org $::emitter(pos.x)
set y_org $::emitter(pos.y)
set xStart [expr {$x_org + $::particle($me,prevPos.x)}]
set yStart [expr {$y_org + $::particle($me,prevPos.y)}]
set xEnd [expr {$x_org + $::particle($me,pos.x)}]
set yEnd [expr {$y_org + $::particle($me,pos.y)}]
.c1 coords $me $xStart $yStart $xEnd $yEnd
.c1 itemconfigure $me -fill [createColor $::particle($me,color.r) \
$::particle($me,color.g) $::particle($me,color.b)]
return 1
}}
proc createColor {r g b} {
# --- convert all passed vals to ints
set r [expr {int($r)}]
set g [expr {int($g)}]
set b [expr {int($b)}]
# --- push colors within valid range
if {$r > 255} {set r 255}
if {$g > 255} {set g 255}
if {$b > 255} {set b 255}
if {$r < 0} {set r 0}
if {$g < 0} {set g 0}
if {$b < 0} {set b 0}
# --- return a TK acceptable color string
return [format "#%02x%02x%02x" $r $g $b]}
# --- this lacks *a lot*. It should allow GUI access to a total of # 26 emitter variables, not just 3 - maybe someday... proc buildUI {} {
canvas .c1 -bg black -width 600 -height 400 -highlightthickness 0 -borderwidth 0
frame .f1
pack .c1 -side left -fill both -expand 1
pack .f1 -side left -fill y -expand 1
scale .f1.s1 -from 1 -to 500 -label "Max Particles" -length 100 -showvalue 1 \
-orient horizontal -width 8 -sliderlength 15 -variable ::emitter(totalParticles)
scale .f1.s2 -from -5 -to 5 -label "Wind" -length 100 -showvalue 1 \
-orient horizontal -width 8 -sliderlength 15 -variable ::emitter(force.x) -resolution .1
scale .f1.s3 -from -5 -to 5 -label "Gravity" -length 100 -showvalue 1 \
-orient horizontal -width 8 -sliderlength 15 -variable ::emitter(force.y) -resolution .1
button .f1.btnExit -text "Exit" -width 10 -command {set ::emitter(alive) 0}
pack .f1.s1 .f1.s2 .f1.s3
pack .f1.btnExit -side bottom
bind .c1 <B1-Motion> {updateEmitterLoc %x %y}
bind .c1 <ButtonPress-1> {updateEmitterLoc %x %y}
wm title . "Particle System Editor"}
# --- generate a random in the range of "-1 to < 1" proc randomNum {} {
return [expr {(-.5 + rand()) * 2.0}]}
proc degreeToRad {degrees} {
return [expr {$degrees / 57.2957795786}]}
# --- move the emitter to the specifiec location proc updateEmitterLoc {x y} {
set ::emitter(pos.x) $x
set ::emitter(pos.y) $y}
proc rotationToDirection {pitch yaw} {
set x [expr {-sin($yaw) * cos($pitch)}]
set y [expr {sin($pitch)}]
set z [expr {cos($pitch) * cos($yaw)}]
return [list $x $y $z]}
main