HSV Mapping

Animation control:

Visualization	Frame Value
Surface geometry	sectioning parameter per frame
Surface position	fixed to the coordinate axis
Surface color	constant
Shading and highlighting	fixed to the coordinate axis
Axis coordinate	constant

This is a composite surface of Planar, Polar and Cylindrical surfaces. As a result, a single-color mapping function is used instead of defining three separate functions which would be required if treated separately, one for each surface native coordinate system.

Note

Any composite surface uses a xyz coordinate system.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
import s3dlib.surface as s3d

#.. HSV Color Space Animation

# 0. Define animation control parameters ............................

frameSetSize = 30       # numb frames in each transition phase
totalTime, numFrames = 12, 4*frameSetSize         # time in seconds
frames=range(numFrames) 
interval = int(1000.0*totalTime/numFrames)       # milliseconds

# 1. Define function to examine .....................................

def xyz2hsv(xyz,rot) :
    # hsv color cylinder from -1<z<1, 0<R<1
    x,y,z = xyz
    theta = np.arctan2(y,x)
    theta = np.where(theta<0,theta+2*np.pi,theta)
    h = np.mod( rot + theta/(2*np.pi), 1.0 )
    s = np.sqrt( x**2 + y**2)
    v = ( z + 1 ) /2.0  
    return h,s,v

def get_surface(Z1TSTE_a) :
    z1, ts, te, ag = Z1TSTE_a
    # ts, te - theta start, end
    def outsideface(rtz, Zm, Ts, Te, isTop=True) :
        r,t,z = rtz
        T = (Te-Ts)*t + 2*np.pi*Ts
        T = np.mod(T,2*np.pi)
        if isTop : Z = np.full(len(z),Zm)
        else:      Z = (Zm+1)*z/2 + (Zm-1)/2
        return r,T,Z
    def insideface(xyz, Zm, T, back=1) :
        x,y,z = xyz
        A = ( x + 1.0 )/2.0
        Z = back*(Zm+1)*y/2 + (Zm-1)/2
        X = A*np.cos(T*2*np.pi) 
        Y = A*np.sin(T*2*np.pi) 
        return X,Y,Z

    rez=5
    front = s3d.PlanarSurface(rez,color='C0')
    front.map_geom_from_op(lambda xyz : insideface(xyz,z1,ts))
    back = s3d.PlanarSurface(rez,color='C1')
    back.map_geom_from_op(lambda xyz : insideface(xyz,z1,te,-1))
    top = s3d.PolarSurface(rez,basetype='hex_c',color='C2')
    top.map_geom_from_op(lambda rtz : outsideface(rtz,z1,ts,te))
    side = s3d.CylindricalSurface(rez,basetype='tri_s',color='C3')
    side.map_geom_from_op(lambda rtz : outsideface(rtz,z1,ts,te,False))
    surface = front+back+top+side
    surface.map_color_from_op(lambda xyz : xyz2hsv(xyz,ag), rgb=False )
    surface.shade(0.925)
    return surface

def get_frames(n) :
    negmin = -0.9999
    ts_0 = 1/12
    te_0 = 1 + ts_0
    ts_f,te_f = 1/3, 5/6
  
    z = np.linspace(negmin, 1.0, n)
    z = np.concatenate( ( z, np.full(2*n,1.0) ) )
    z = np.concatenate( ( z, np.linspace( 1.0, negmin, n) ) )
    
    ts = np.full(n,ts_0)
    ts = np.concatenate( ( ts, np.linspace( ts_0, ts_f, n) ) )
    ts = np.concatenate( ( ts, np.full(n,ts_f) ) )
    ts = np.concatenate( ( ts, np.linspace( ts_f, ts_0, n) ) )

    te = np.full(n,te_0)
    te = np.concatenate( ( te, np.linspace( te_0, te_f, n) ) )
    te = np.concatenate( ( te, np.full(n,te_f) ) )
    te = np.concatenate( ( te, np.linspace( te_f, te_0, n) ) )

    a =  np.zeros(2*n)
    a =  np.concatenate( ( a,  np.linspace( 0,   1.0, 2*n) ) )

    return np.transpose([z,ts,te,a])

framearray = get_frames(frameSetSize)

# 2. Setup and map surfaces .........................................
fID = 0
surface = get_surface(framearray[fID])
floor = s3d.PolarSurface.grid(1,30,color='.9').domain(zcoor=-1.001)

# 3. Construct figure, add surface, plot ............................

fig = plt.figure(figsize=plt.figaspect(1),constrained_layout=True)
fig.text(0.05,0.05,str(surface), ha='left', va='bottom', fontsize='smaller')
ax = plt.axes(projection='3d', aspect='equal', proj_type='ortho')
ax.set(xlim=(-1,1), ylim=(-1,1), zlim=(-1,1) )
ax.set_axis_off()
ax.view_init(azim=30)

ax.add_collection3d(surface)
ax.add_collection3d(floor)

#plt.show()

# 4. Animation ======================================================

def update_fig(frame):
    global surface

    surface.remove()
    surface = get_surface( framearray[frame] )

    ax.add_collection3d(surface)
    return

anim = FuncAnimation(fig, update_fig, frames, interval=interval, repeat=True)
anim.save('hsv_cylinder.html',writer='html')

msg = "saved {} frames, values: [{:.3f} to {:.3f}] @ {} milliseconds/frane"
print(msg.format(numFrames,np.min(frames),np.max(frames),interval))