WorldViz User Forum  

Go Back   WorldViz User Forum > Vizard

Thread Tools Rating: Thread Rating: 2 votes, 5.00 average. Display Modes
Old 05-07-2013, 06:53 AM
4711 4711 is offline
Join Date: Jan 2010
Posts: 15
Fluent viewpoint rotation towards an object

Hi everybody,

I have a simple question:

How can I fluently turn the viz.MainView towards an object somewhere in my environment (without knowing the angle between the current viewing direction and the object)?

I could do all the math behind such a rotation myself, but I guess there's a smarter and much shorter way to achive that with Vizard's built-in methods. What I'm looking for is basically what the "viz.MainView.lookAt" function already does, extended by the possibility for a fluent movement instead of the discrete jump in viewing direction.

Can anybody help me out with a good idea?

Thanks in advance!
Reply With Quote
Old 05-07-2013, 08:41 AM
farshizzo farshizzo is offline
WorldViz Team Member
Join Date: Mar 2003
Posts: 2,849
Are you using Vizard 3 or 4?

If you are using Vizard 4, then you can use the vizact.spinTo action to animate the viewpoint to look towards a specific point. Example:
# Animate looking at specified point for half a second
lookAtAction = vizact.spinTo(point=(0,1.8,8),time=0.5,interpolate=vizact.easeOut)

# Add action to main view
Reply With Quote
Old 05-07-2013, 09:14 AM
4711 4711 is offline
Join Date: Jan 2010
Posts: 15

thanks for the quick reply. I'm running my script under Vizard 3, since large parts were written before the release of Vizard 4. Unfortunately, it seems like your code doesn't produce the result it's supposed to in Vizard 3.

Is there any other possibility how this could work in Vizard 3?
Reply With Quote
Old 05-09-2013, 08:12 AM
farshizzo farshizzo is offline
WorldViz Team Member
Join Date: Mar 2003
Posts: 2,849
You can still use the spinto action in Vizard 3, however you will need to manually calculate the final rotation to spinto. You can do this by saving the main views current rotation, call the lookat function and save the new rotation, then restore the previous rotation.
Reply With Quote
Old 05-23-2013, 02:58 AM
4711 4711 is offline
Join Date: Jan 2010
Posts: 15

I can't see how quickly setting the viewpoint towards the object via "lookat()" and then set it back again to the original direction can work without resulting in a short flickering in the viewpoint. Maybe I got you wrong?
Reply With Quote
Old 05-23-2013, 03:20 AM
4711 4711 is offline
Join Date: Jan 2010
Posts: 15
I wrote some code myself to solve the problem:

import math
import viz


def Angle2Euler( angle ):
	euler = 0
	# Not defined for negative values
	if angle < 0:
		return 0
	# Calculate 'euler' depending on quadrant
		if angle <= 90:
			# Q1
			euler = 90 - angle
		elif angle <= 270:
			# Q2 & Q3
			euler = -( angle-90 )
			# Q4
			euler = 360 - angle + 90
	return euler

def Cart2Pol( x, y, unit='rad' ):
	# Radius
	r = math.sqrt( math.pow(x,2) + math.pow(y,2) )
	# Angle in [rad]
	t = math.atan2( y ,x )
	# Angle in [deg]
	if unit.lower() == 'deg':
		t = math.degrees( math.atan(float(y)/float(x)) )
		if x < 0:
			t += 180 # Q2 & Q3
		elif x > 0 and y < 0:
			t += 360 # Q4
	return r, t

def LookAt( Target ):

	# Get current position and orientation
	Pos = viz.MainView.getPosition()
	Ori = viz.MainView.getEuler()
	# Define position as 2D point 'P'
	P = [Pos[0], Pos[2]]
	# Define target as 2D point 'T'
	T = [Target[0], Target[2]]
	# Shift 'P' into origin (= 'P0') and
	# move 'T' accordingly (= 'T0')
	T0 = [T[0]-P[0], T[1]-P[1]]

	# Get location of 'T0' as polar angle
	angle = Cart2Pol( T0[0], T0[1], 'deg' )[1]
	# Convert angle to Vizard's Euler style
	euler = Angle2Euler( angle )
	# Create rotation action towards target
	rotation = vizact.spinTo( euler=[euler,0,0], time=2 )
	# Apply rotation to MainView
	viz.MainView.runAction( rotation )

# --- AN EXAMPLE --- #

# Go!

# Add a box behind the MainView
box = viz.add('box.wrl')

# Look at the box
LookAt( box.getPosition() )
This may not be the easiest or most elegant way, but it works!
Reply With Quote

fluent, rotation, viewpoint

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
load a texture on a object of a viewpoint Darkmax Vizard 1 11-12-2010 11:52 AM
limiting object rotation Philippe Vizard 5 10-07-2010 04:31 PM
How to make an object fixed in viewpoint coordinate system? Xianshi Xie Vizard 1 06-22-2009 11:31 AM
Object rotation Andrey Vizard 4 06-13-2007 02:49 PM
Child Object Rotation paulgoldberg Vizard 5 09-05-2006 11:33 AM

All times are GMT -7. The time now is 12:35 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright 2002-2018 WorldViz LLC