Relative H (from hpr) in Panda3d

Hi I am planning to modify the Roaming Ralph Game.
I want to introduce panda into the game.

I made panda follow ralph, but the panda is watching only in one direction.
How can I change its H (from hpr) so that it always watch the running ralph.

Thank you.!!

You can use the lookAt function for this.

Why not just reparent camera node to the ralph node?
I think, itâ€™s the simpliest way to make a 3rd-person camera.

I am using lookAt but then the panda is watching in exactly opposite direction.
How to turn it on 180 degrees ?

Just after loading the model, you can call setH(180) and then call flattenLight() to bake the transformation into the vertices.

Alternatively, you can reparent it to a dummy node and give it a 180 degree rotation relative to the dummy node.

``````# Author: Ryan Myers
# Models: Jeff Styers, Reagan Heller

# Last Updated: 6/13/2005
#
# This tutorial provides an example of creating a character
# and having it walk around on uneven terrain, as well
# as implementing a fully rotatable camera.

import direct.directbase.DirectStart
from panda3d.core import CollisionTraverser,CollisionNode
from panda3d.core import CollisionHandlerQueue,CollisionRay
from panda3d.core import Filename,AmbientLight,DirectionalLight
from panda3d.core import PandaNode,NodePath,Camera,TextNode
from direct.gui.OnscreenText import OnscreenText
from direct.actor.Actor import Actor
import math
from direct.showbase.DirectObject import DirectObject
import random, sys, os, math

SPEED = 0.5

#A simple function to make sure a value is in a given range, -1 to 1 by default
def restrain(i, mn = -1, mx = 1): return min(max(i, mn), mx)

# Function to put instructions on the screen.
return OnscreenText(text=msg, style=1, fg=(1,1,1,1),
pos=(-1.3, pos), align=TextNode.ALeft, scale = .05)

# Function to put title on the screen.
return OnscreenText(text=text, style=1, fg=(1,1,1,1),
pos=(1.3,-0.95), align=TextNode.ARight, scale = .07)

class World(DirectObject):

def __init__(self):

self.keyMap = {"left":0, "right":0, "forward":0, "cam-left":0, "cam-right":0}
base.win.setClearColor(Vec4(0,0,0,1))

# Post the instructions

self.title = addTitle("Panda3D Tutorial: Roaming Ralph (Walking on Uneven Terrain)")
self.inst2 = addInstructions(0.90, "[Left Arrow]: Rotate Ralph Left")
self.inst3 = addInstructions(0.85, "[Right Arrow]: Rotate Ralph Right")
self.inst4 = addInstructions(0.80, "[Up Arrow]: Run Ralph Forward")
self.inst6 = addInstructions(0.70, "[A]: Rotate Camera Left")
self.inst7 = addInstructions(0.65, "[S]: Rotate Camera Right")

# Set up the environment
#
# This environment model contains collision meshes.  If you look
# in the egg file, you will see the following:
#
#    <Collide> { Polyset keep descend }
#
# This tag causes the following mesh to be converted to a collision
# mesh -- a mesh which is optimized for collision, not rendering.
# It also keeps the original mesh, so there are now two copies ---
# one optimized for rendering, one for collisions.

self.environ.reparentTo(render)
self.environ.setPos(0,0,0)

# Create the main character, Ralph

ralphStartPos = self.environ.find("**/start_point").getPos()
self.ralph = Actor("models/ralph",
{"run":"models/ralph-run",
"walk":"models/ralph-walk"})
self.ralph.reparentTo(render)
self.ralph.setScale(.2)
self.ralph.setPos(ralphStartPos)
ralphStartPos.setY(ralphStartPos.getY()-10)
self.ralph.setPos(ralphStartPos.getX(),ralphStartPos.getY(),ralphStartPos.getZ())
self.initx = ralphStartPos.getX()

# Load and transform the panda actor.
self.pandaActor = Actor("models/panda-model",
{"walk": "models/panda-walk4"})
self.pandaActor.setScale(0.003, 0.003, 0.003)
self.pandaActor.reparentTo(render)
# Loop its animation.
self.pandaActor.loop("walk")
self.pandaActor.setPos(ralphStartPos.getX(),ralphStartPos.getY()-20,ralphStartPos.getZ())

# Create a floater object.  We use the "floater" as a temporary
# variable in a variety of calculations.

self.floater = NodePath(PandaNode("floater"))
self.floater.reparentTo(render)

# Accept the control keys for movement and rotation

self.accept("escape", sys.exit)
self.accept("arrow_left", self.setKey, ["left",1])
self.accept("arrow_right", self.setKey, ["right",1])
self.accept("arrow_up", self.setKey, ["forward",1])
self.accept("a", self.setKey, ["cam-left",1])
self.accept("s", self.setKey, ["cam-right",1])
self.accept("arrow_left-up", self.setKey, ["left",0])
self.accept("arrow_right-up", self.setKey, ["right",0])
self.accept("arrow_up-up", self.setKey, ["forward",0])
self.accept("a-up", self.setKey, ["cam-left",0])
self.accept("s-up", self.setKey, ["cam-right",0])

# Game state variables
self.isMoving = False

# Set up the camera

base.disableMouse()
base.camera.setPos(self.ralph.getX(),self.ralph.getY()+10,2)

# We will detect the height of the terrain by creating a collision
# ray and casting it downward toward the terrain.  One ray will
# start above ralph's head, and the other will start above the camera.
# A ray may hit the terrain, or it may hit a rock or a tree.  If it
# hits the terrain, we can detect the height.  If it hits anything
# else, we rule that the move is illegal.

self.cTrav = CollisionTraverser()

self.ralphGroundRay = CollisionRay()
self.ralphGroundRay.setOrigin(0,0,1000)
self.ralphGroundRay.setDirection(0,0,-1)
self.ralphGroundCol = CollisionNode('ralphRay')
self.ralphGroundColNp = self.ralph.attachNewNode(self.ralphGroundCol)
self.ralphGroundHandler = CollisionHandlerQueue()

self.pandaActorGroundRay = CollisionRay()
self.pandaActorGroundRay.setOrigin(0,0,1000)
self.pandaActorGroundRay.setDirection(0,0,-1)
self.pandaActorGroundCol = CollisionNode('pandaActorRay')
self.pandaActorGroundColNp = self.pandaActor.attachNewNode(self.pandaActorGroundCol)
self.pandaActorGroundHandler = CollisionHandlerQueue()

self.camGroundRay = CollisionRay()
self.camGroundRay.setOrigin(0,0,1000)
self.camGroundRay.setDirection(0,0,-1)
self.camGroundCol = CollisionNode('camRay')
self.camGroundColNp = base.camera.attachNewNode(self.camGroundCol)
self.camGroundHandler = CollisionHandlerQueue()

# Uncomment this line to see the collision rays
#self.ralphGroundColNp.show()
#self.camGroundColNp.show()

# Uncomment this line to show a visual representation of the
# collisions occuring
#self.cTrav.showCollisions(render)

# Create some lighting
ambientLight = AmbientLight("ambientLight")
ambientLight.setColor(Vec4(.3, .3, .3, 1))
directionalLight = DirectionalLight("directionalLight")
directionalLight.setDirection(Vec3(-5, -5, -5))
directionalLight.setColor(Vec4(1, 1, 1, 1))
directionalLight.setSpecularColor(Vec4(1, 1, 1, 1))
render.setLight(render.attachNewNode(ambientLight))
render.setLight(render.attachNewNode(directionalLight))

#Records the state of the arrow keys
def setKey(self, key, value):
self.keyMap[key] = value

# Accepts arrow keys to move either the player or the menu cursor,
# Also deals with grid checking and collision detection

# If the camera-left key is pressed, move camera left.
# If the camera-right key is pressed, move camera right.

base.camera.lookAt(self.ralph)
if (self.keyMap["cam-left"]!=0):
base.camera.setX(base.camera, -20 * globalClock.getDt())
if (self.keyMap["cam-right"]!=0):
base.camera.setX(base.camera, +20 * globalClock.getDt())

# save ralph's initial position so that we can restore it,
# in case he falls off the map or runs into something.

startpos = self.ralph.getPos()

# If a move-key is pressed, move ralph in the specified direction.

if (self.keyMap["left"]!=0):
self.ralph.setH(self.ralph.getH() + 300 * globalClock.getDt())
if (self.keyMap["right"]!=0):
self.ralph.setH(self.ralph.getH() - 300 * globalClock.getDt())
if (self.keyMap["forward"]!=0):
self.ralph.setY(self.ralph, -25 * globalClock.getDt())

#Panda Moving Towards Ralph
if (self.ralph.getX() < self.pandaActor.getX()):
self.pandaActor.setX(self.pandaActor, -1000 * globalClock.getDt())

if (self.ralph.getX() > self.pandaActor.getX()):
self.pandaActor.setX(self.pandaActor, 1000 * globalClock.getDt())

if (self.ralph.getY() < self.pandaActor.getY()):
self.pandaActor.setY(self.pandaActor, -1000 * globalClock.getDt())

if (self.ralph.getY() > self.pandaActor.getY()):
self.pandaActor.setY(self.pandaActor, 1000 * globalClock.getDt())

self.pandaActor.lookAt(self.ralph)
# If ralph is moving, loop the run animation.
# If he is standing still, stop the animation.

if (self.keyMap["forward"]!=0) or (self.keyMap["left"]!=0) or (self.keyMap["right"]!=0):
if self.isMoving is False:
self.ralph.loop("run")
self.isMoving = True
else:
if self.isMoving:
self.ralph.stop()
self.ralph.pose("walk",5)
self.isMoving = False

# If the camera is too far from ralph, move it closer.
# If the camera is too close to ralph, move it farther.

camvec = self.ralph.getPos() - base.camera.getPos()
camvec.setZ(0)
camdist = camvec.length()
camvec.normalize()
if (camdist > 10.0):
base.camera.setPos(base.camera.getPos() + camvec*(camdist-10))
camdist = 10.0
if (camdist < 5.0):
base.camera.setPos(base.camera.getPos() - camvec*(5-camdist))
camdist = 5.0

# Now check for collisions.

self.cTrav.traverse(render)

# Adjust ralph's Z coordinate.  If ralph's ray hit terrain,
# update his Z. If it hit anything else, or didn't hit anything, put
# him back where he was last frame.

entries = []
for i in range(self.ralphGroundHandler.getNumEntries()):
entry = self.ralphGroundHandler.getEntry(i)
entries.append(entry)
entries.sort(lambda x,y: cmp(y.getSurfacePoint(render).getZ(),
x.getSurfacePoint(render).getZ()))
if (len(entries)>0) and (entries[0].getIntoNode().getName() == "terrain"):
self.ralph.setZ(entries[0].getSurfacePoint(render).getZ())
else:
self.ralph.setPos(startpos)

entries2 = []
for i in range(self.pandaActorGroundHandler.getNumEntries()):
entry = self.pandaActorGroundHandler.getEntry(i)
entries2.append(entry)
entries2.sort(lambda x,y: cmp(y.getSurfacePoint(render).getZ(),
x.getSurfacePoint(render).getZ()))
if (len(entries2)>0) and (entries2[0].getIntoNode().getName() == "terrain"):
self.pandaActor.setZ(entries2[0].getSurfacePoint(render).getZ())
else:
self.pandaActor.setPos(startpos)

# Keep the camera at one foot above the terrain,
# or two feet above ralph, whichever is greater.

entries = []
for i in range(self.camGroundHandler.getNumEntries()):
entry = self.camGroundHandler.getEntry(i)
entries.append(entry)
entries.sort(lambda x,y: cmp(y.getSurfacePoint(render).getZ(),
x.getSurfacePoint(render).getZ()))
if (len(entries)>0) and (entries[0].getIntoNode().getName() == "terrain"):
base.camera.setZ(entries[0].getSurfacePoint(render).getZ()+1.0)
if (base.camera.getZ() < self.ralph.getZ() + 2.0):
base.camera.setZ(self.ralph.getZ() + 2.0)

# The camera should look in ralph's direction,
# but it should also try to stay horizontal, so look at
# a floater which hovers above ralph's head.

self.floater.setPos(self.ralph.getPos())
self.floater.setZ(self.ralph.getZ() + 2.0)
base.camera.lookAt(self.floater)