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Editor Documentation

Introduction

This basic introduction will help you start the editor, load a demo file, run a simulation, move the camera and maybe tweak some parameters to see how they effect the simulation.

It is assumed that you have read the ODE documentation.

Unzipping the package

Download the latest EZPhysics Editor file from here anywhere onto your disk. It will open a directory called EZPhysics in which you will find Media and Release subdirectories.

Running the application

►Run the application EZPhysicsEditor.exe

Select your Ogre Rendering System Options by highlighting each line and setting your configuration parameters. Set the “Full Screen” option to “No”.

►File->Open the file EZPhysicsDemo1.sim located in the Media directory. You should have two windows now, one with the editor and one with the Ogre scene. On the left tree, select the Scene node called rope.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

►Press the Start button and the simulation will start. This is an upside-down rope that’s “grounded” to its base. Depending on your CPU and graphics processor, if the simulation is too fast, you may want to change the constant step size from 0.1 to 0.02 to see the simulation go slower. Press Stop and Start to restart the simulation.

►Change the level of detail of the scene by selecting:
- Texture under Mesh
- None under Proxy
- None under Joint
You will only see the green rope now. If you run the simulation again, it may look more like a rubber rope falling under the influence of gravity. Each Mesh in the scene has its own level of detail that can either be inherited from the parent or be independent.

►Right-click on the Bone node called Bone01 under the rope_up Mesh node and add a Sphere Proxy. It will show up at the bottom of the tree so you may want to right-click it and select “Move Up” so that it will be situated under the Bone node as in the picture below. Change the Radius from 1 to 10. To get a closer look at the sphere click on the Ogre Scene window and move the mouse while pressing the mouse left and right buttons with and without the left CTRL button pressed. You will understand their effects.. Hopefully you have a mouse with a middle wheel button. Another motion effect is achieved by pressing the left mouse while rolling the middle wheel.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Run the simulation again and see the effect of adding the heavy sphere at the end of the rope.

►Right-click the rope_up (Mesh) node and select “Copy” from the menu. Now right-click the rope (Scene) node and select “Paste”. This has created another Mesh node under the rope Scene node, called rope_up_5 (or some other random number). Select the new Mesh node and change the displacement value dX from 0 to 10. The second rope becomes visible.  Select the Scene node rope and run the simulation again.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

►Check out other Scenes in the object tree. You will recognize the one called taxi if you have already run EZPhysicsDemo1.exe.

 

Mouse and Keyboard commands

Left-MouseButton + Mouse-move—Turn X/Y around Focus

Left-MouseButton + MouseWheel—Turn Z around Focus

Left-MouseButton + LCTRL—Turn Focus X/Y around you

Moving Proxy objects is done either by selecting the tree item and changing the properties in the panel or using the following keyboard keys while the graphics window is highlighted:

Q,W,A,S,Z,X—Proxy Rotation

O,P,K,L,N,M—Proxy Translation

The Object Tree

In general, most tree actions are done via mouse right-click. Copy/Paste is useful for copying proxies and bodies that have been physically rigged.

►World—global system parameters, mostly Ogre related. Right-Clicking on World allows adding a Body (Mesh file) or a Scene.

►Graphics—The graphics node is a container of a set of meshes with known names. These are the base meshes used to display proxies, joints bounding box etc.

►Body—Associated with a mesh file. If the mesh file has a skeleton, it will show up as a sub-tree of bones under that body. A body can have two types of collision detection: proxies—means that the set of proxies embedded in the body’s mesh will do the collision. Mesh—means that the actual mesh of the body will be use for collision.
The mass of the body has, however, to be defined by the proxies embedded in it. Skeletal animated bodies that are rigged with joints wont collide as expected if collision is set to mesh because mesh collision detection is done by the CPU while normally skeletal animation is done by the graphics card and transferring the data is inefficient if frame-rate is of essence.

►Bone—Skeletal Meshes have bones, moving the bones gets the “Skin” turning accordingly. This feature is usually used for pre-programmed animation. EZPhysics uses bones as objects that contain physical entities. Proxies are attached to bones and a joint can be connected between two bones that have proxies.

►Scene—A Scene contains multiple bodies. Normally you load new bodies under World, tweak them around, add proxies and joints, and then copy them into a Scene. Only a scene can be simulated (a body on its own can not).

►Proxies—Basic physics objects. They serve for both Collision detection and as Dynamics objects with inertia tensor, speed etc. Multiple proxies can be associated to a single bone in order for the bunch to more closely resemble the skinned mesh that surrounds the bone.

►Joints—Objects that limit the freedom of movement of the bones (that have proxies attached to them). Joints have virtual motors that can be manipulated by the API to create interesting movement (used for steering the wheels of a car, to simulate a spider’s gait, to get biped robots to walk etc.)

►Controls—If you wish to apply forces and torques on joints during simulation  using the keyboard, you can map keys to joint axis and apply a predetermined mount of force every time you press the key. This is useful to control the speed of a car or it wheels for example.

§Most nodes have an optional camera. The camera can be configured to follow moving objects and focus on possibly different moving objects.

§Some nodes allow you to configure the level of visual detail. This determines if you will see the proxies, meshes, bounding boxes etc. Their transparency is defined as well as their scale.

§When an object in the tree is selected, the camera and level of visual detail is taken from the node at or above the selected one, where the visual-detail and/or camera are enabled.

 

EZPhysics