//Example Gear Train System Equation Use
Many gear train system types setup with different uses of general gear equations and parameters to show different uses.
Has some general gear terminology and shows/describes them in a very basic and easy to understand manner.
//Creating Basic Billboard Mesh Through Unity Scripting
Shows how to create a vertex array, set these into triangles, and create a full mesh.
This shows that it is possible to create/modify meshes within Unity using scripting.
This may be possible through the general use of the Mesh class in Unity scripting. Something along the lines of creating a set of vertices for the central body (some smoothness level of cylinder), then creating a gear tooth mesh that can be multiplied and geometrically positioned around the central core body mesh created.
“Normal Maps and Height Maps are both types of Bump Map. They both contain data for representing apparent detail on the surface of simpler polygonal meshes, but they each store that data in a different way. A height map is a simple black and white texture, where each pixel represents the amount that point on the surface should appear to be raised. The whiter the pixel colour, the higher the area appears to be raised.
A normal map is an RGB texture, where each pixel represents the difference in direction the surface should appear to be facing, relative to its un-modified surface normal. These textures tend to have a bluey-purple tinge, because of the way the vector is stored in the RGB values.”
Unity Displacment Maps and Tesselation
//Using Maya, I was able to create a very basic cam mechanism using a basic cylinder as the main body, and moving a few of the edges symmetrically to create a more interesting shape for the follower to follow as it rotated.
The follower for this cam-follower system is just a generic Unity cube game Object for now, with a basic box collider. This setup appeared to work well for this basic cam-follower mechanism. There was a bit of a difference in the way this cam was imported into Unity as opposed to the gear, which will need looked into. Its polySurface, which contains the mesh of the object, is a separate and child object of the actual “Cam_Basic_Unity” export.
The following video shows the cam-follower system in action.
//This is a book by Krishna Kumar going over the basics of PhysX as a physics engine. Could be useful for better understanding the default physics engine, PhysX, to properly drive engineering mechanisms.
“Finite element analysis is a basic foundational topic that all engineering majors need to understand in order for them to be productive engineering analysts for a variety of industries. This book provides an introductory treatment of finite element analysis with an overview of the various fundamental concepts and applications. It introduces the basic concepts of the finite element method and examples of analysis using systematic methodologies based on ANSYS software.”
This could be useful for learning and using finite element analysis, if looking into real time finite element analysis for use in games.
Wikipedia page for Physics Engines
//As was mentioned in the last post, it seems that it was effective to save an original copy of models of mechanisms in Maya with the past transforms and history in tact to edit to create modified versions of said object. Using this, I was able to create another gear that simply had double the radius of the original, and export that model to Unity as a separate object.
It is important to note that the initial collider may not always be at 0 degrees. It may be offset by several degrees. This was determined by visually lining up the first collider with a few different degrees until it appeared to be correct, then the calculated &Theta values were added to this initially discovered value (instead of the assumed zero).
Using the previously described techniques for modeling gears, two gears of different radius values were created to set in Unity (R = 0.5 and R = 1.0). These were all setup with Rigidbody components, and parented to colliders representing all of the teeth, using the above method. Both object’s rigidbody components froze every constraint except for “Rotation on the y-axis (Those frozen include: movement in x,y,z and rotation on x, z). The larger gear was given a basic script that caused it to rotate about the Y-axis over time. It was hoped that this could be placed in a way that rotating this large gear would cause the colliders between the two gears to interact and physically rotate the second gear. Below is a video of it in action.
//The scaling between Maya and Unity can act a bit strangely. It appears to be because Unity treats its units as “meters” by default, and Maya treats its units in “centimeters” by default. This guide helps in figuring out how to set up your Maya work file and its export, along with the Unity import, so that the scaling of objects makes sense.
Directly from the guide: “The best reason I can figure from all the posts on the web is that Maya’s native units are centimeters and that is how it “thinks” about its scenes. Anything exporting FROM Maya will essentially be in centimeters, so even though we set the scale of our objects to Meters, they are actually still in centimeters. The FBX, however, doesn’t really care about scale. It will, however, pull the relative scale value out based on what you are trying to export it as. In this case, we have a centimeter based file and we want it to actually be in Meters, so we need to multiply everything by 100 in order to get it sized properly.”
//The basics of gear ratios.
This site includes a list of many parameters involved in gear design, and some of the general equations to obtain them.
This site shows all of the different types of gears and gear mechanisms in a very basic fashion with short descriptions of the general uses for each of them.