func (scheme SchemeBits) Color(x, y float32) (r, g, b float32) {
if scheme&RealBit == 0 {
x = 0
}
if scheme&ImagBit == 0 {
y = 0
}
θ := math32.Atan2(-y, x)
d := math32.Hypot(x, y)
if d > 1 || scheme&MagnitudeBit == 0 {
d = 1.0
}
if scheme&PhaseBit == 0 {
r, g, b = d, d, d
} else {
r, g, b = phaseColor(θ)
r *= d
g *= d
b *= d
}
if scheme&RedBit == 0 {
r = 0
}
if scheme&GreenBit == 0 {
g = 0
}
if scheme&BlueBit == 0 {
b = 0
}
return
}
// Set maximum absolute velocity to v pixels per second.
func SetVelocityMax(v float32) {
velocityMax = v
for k := 1; k < len(Zoo); k++ {
c := &Zoo[k]
u := math32.Hypot(c.vx, c.vy)
if u > 0.001 {
// Scale velocity to new max
f := velocityMax / u
c.vx *= f
c.vy *= f
} else {
// Critter is essentially stationary. Give it a new velocity.
c.initAlienVelocity()
}
}
}
// drawFrequonsSpatial draws the spatial-domain representation of Frequons.
// (xf,yf) is the location of the player.
func drawFrequonsSpatial(pm nimble.PixMap, xf, yf int32) {
nPastel := pastels.Width()
for k := 1; k < len(universe.Zoo); k++ {
c := &universe.Zoo[k]
d := int32(math32.Hypot(float32(xf)-c.Sx, float32(yf)-c.Sy))
if c.Show || d < nPastel {
i := c.ImageIndex()
if i < len(critterSeq[k]) {
j := int32(0)
if !c.Show {
j = d
}
sprite.Draw(pm, int32(math32.Round(c.Sx)), int32(math32.Round(c.Sy)), critterSeq[k][i], pastels.Pixel(j, int32(c.Id)))
}
}
}
if fourierPort.Contains(mouseX, mouseY) {
sprite.Draw(pm, xf, yf, critterSeq[0][0], nimble.White)
}
}
func makeFragments(radius int, self bool) (frags []fragment) {
r := float32(radius)
for y := -r; y <= r; y++ {
for x := -r; x <= r; x++ {
d := math32.Hypot(x, y)
var includePoint bool
if self {
// Self is hollow ring
includePoint = r*0.9 <= d && d <= r*1.1
} else {
// Aliens are solid circles
includePoint = d <= r
}
if includePoint {
// Impart radial velocity to fragment
var vx, vy, extra float32
if d > 0 {
vx, vy = x/d, y/d
extra = 0.4
} else {
vx, vy = 0, 0
extra = 1.4
}
// Random non-radial component
uy, ux := math32.Sincos(rand.Float32() * (2 * math32.Pi))
frags = append(frags, fragment{
x,
y,
vx + ux*extra,
vy + uy*extra,
})
}
}
}
return frags
}
