Description
A moving rope-node, with the "tape" render-mode applied, can produce small overlaps and breaks along its course. This is most especially the case when it turns acutely, I find.
Steps to Reproduce
The following program demonstrates the effect, on my machine at least. To test, simply run the program--you should see a flat rope-node moving in a circle of varying diameter, and triangular breaks and overlaps appearing. (The latter made visible via transparency and a lack of depth-testing)
from direct.showbase.ShowBase import ShowBase
from panda3d.core import Vec3, Vec4, NodePath, RopeNode, NurbsCurveEvaluator
import math
from panda3d import __version__ as pandaVersion
print (pandaVersion)
import sys
print (sys.version)
class Game(ShowBase):
def __init__(self):
ShowBase.__init__(self)
# A black backdrop to better show the effect
self.win.setClearColor(Vec4(0, 0, 0, 1))
# Our rope and its curve!
self.ropeNode = RopeNode("rope")
self.curve = NurbsCurveEvaluator()
self.ropeNode.setCurve(self.curve)
# Make the rope a flat surface, and set its width
self.ropeNode.setRenderMode(RopeNode.RM_tape)
self.ropeNode.setThickness(3)
# I'm not sure that these are required, but I'll leave them in just in case
self.ropeNode.setNormalMode(RopeNode.NM_none)
self.ropeNode.setTubeUp(Vec3(0, 0, 1))
# Set set up the curve and our number of points
self.curve.reset(7)
# Create and arrange a NodePath for our rope
self.ropeNP = NodePath(self.ropeNode)
self.ropeNP.setY(25)
self.ropeNP.setP(90)
self.ropeNP.reparentTo(render)
# This makes the rope semi-transparent and prevents depth-testing from interfering, as in the original case
self.ropeNP.setAlphaScale(0.5)
self.ropeNP.setTransparency(True)
self.ropeNP.setDepthTest(False)
# For the purposes of this demonstrative program, we'll just have the rope spin around in a circle.
# These next things, then, are elements that control the points of the curve:
# a list of points, a speed-value, and a circle-size (which changes)
self.positionList = []
self.angle = 0
self.speed = 5
self.circleSize = 5
self.maxCircleSize = 5
self.minCircleSize = 1
self.circleSizeDir = 1
# And finally, an update task in which to update our curve
self.updateTask = self.taskMgr.add(self.update, "update task")
def update(self, task):
dt = self.clock.getDt()
# Vary the size of the circle of the rope's movement, to show different aspects of the effect produced
self.circleSize += self.circleSizeDir * 1.5 * dt
if self.circleSizeDir > 0 and self.circleSize > self.maxCircleSize:
self.circleSize = self.maxCircleSize
self.circleSizeDir = -1
elif self.circleSizeDir < 0 and self.circleSize < self.minCircleSize:
self.circleSize = self.minCircleSize
self.circleSizeDir = 1
# Accumulate a circular angle, and from that calculate the current position on the circle
self.angle += self.speed * dt
pos = Vec3(math.sin(self.angle) * self.circleSize, math.cos(self.angle) * self.circleSize, 0)
# Update the list of points:
numPoints = len(self.positionList)
if numPoints == 0:
# If there are no points yet, just add the current one
self.positionList.append(pos)
else:
# Otherwise, if the current point is sufficiently far from the last, add it
lastPt = self.positionList[-1]
diff = pos - lastPt
lastSegmentDist = diff.length()
testDist = 1.5
if lastSegmentDist > testDist:
self.positionList.append(pos)
# Prevent the list from holding too many points
while len(self.positionList) > 8:
self.positionList.pop(0)
# And finally, update the curve!
# The first vertex is always the current point, and subsequent vertices
# take their positions from the point-list
self.curve.setVertex(0, pos)
for index, pt in enumerate(self.positionList[-1:-(len(self.positionList)-1):-1]):
self.curve.setVertex(index+1, pt)
return task.cont
app = Game()
app.run()
Environment
- Operating system: Ubuntu Linux 18.04.6
- System architecture: 64-bit
- Panda3D version: 1.10.11
- Installation method: pip, I believe.
- Python version (if using Python): 3.6.9
- Compiler (if using C++): N/A
Description
A moving rope-node, with the "tape" render-mode applied, can produce small overlaps and breaks along its course. This is most especially the case when it turns acutely, I find.
Steps to Reproduce
The following program demonstrates the effect, on my machine at least. To test, simply run the program--you should see a flat rope-node moving in a circle of varying diameter, and triangular breaks and overlaps appearing. (The latter made visible via transparency and a lack of depth-testing)
Environment