// Init specifies the size of the PixMap seen by subsequent calls to Draw
func Init(width, height int32) {
if width < 0 || height < 0 {
panic(fmt.Sprintf("radar.Init: width=%v height=%v\n", width, height))
}
xSize, ySize = width, height
xScale = 2 / float32(width-1)
yScale = 2 / float32(height-1)
xOffset = 1.0 - xScale*float32(width)
yOffset = 1.0 - yScale*float32(height)
// Allocate clut
clut = make([]rgb, height*width)
// Allocate frames
frameSize = height * width
frameStorage = make([]nimble.Pixel, nFrame*frameSize)
frameValid = make([]bool, nFrame)
// Compute polar coordinates
angle = make([]float32, height*width)
for i := int32(0); i < height; i++ {
for j := int32(0); j < width; j++ {
x := float32(j)*xScale + xOffset
y := float32(i)*yScale + yOffset
if x*x+y*y <= 1 {
angle[i*width+j] = math32.Atan2(-y, x)
} else {
angle[i*width+j] = outsideUnitCircle
}
}
}
}
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
}