We required a mesh fence, to be used multiple times, within our group games environment. I attempted a complete 3D model, using a method where I edited the topology of a grid upon a 3D plane. The resulting diamond shapes were then inset, then bridged to created a mesh effect. Although I was pleased how the model looked, the overall polygon count was immense, too much for a game environment. To try and reduce this count, I researched into alternative methods to acheive a my desired mesh effect.
Due to the fact our game is a 3D side-scroller, the model was only intended to be vied from the front side. I tested the idea of removing polygons which would no be viewable by the player, deleting the complete back side of the model. Although it is evident this would be useful in reducing rendering on certain objects in the future, the model I had created still had more polygons than I desired. This also removes the freedom of being able to use the model in varied situations and positions, as the model would only be able to be viewed from the front.
Mesh Texture using Alpha Channels
I came across the techniques of creating a mesh texture, with the addition of Alpha channels, which when rendered become transparent to the viewer. This would be applied to a single plane, therefore reducing the polygon count from very high numbers to just one or two.
I started by creating a “C” shaped splined rendered to 1cm thickness, which was then mirrored horizontally and overlapped by 1.5cms. I then transformed the separate splines using their vertices along the “Y” axis, moving the top vertex back by -1.5cm and the bottom forward by 1.5cm. I then did the reverse on the mirrored spline to created a chain link effect. Lastly, I cloned the linked shape four more times, using the snap tool to position them precisely, resulting in an easily tillable pattern.
Using the snap to grid tool, I then created two planes on which the model will be projected upon, once baked, provided a Normal Map and Alpha Mask texture. Also, ensuring the plane was coloured complete black and the model complete white to finish the process.
I then applied the projection modifier upon the smaller plane, picking the larger plane and mesh model to project upon it. Ensure the adjust the “cage” of the projection so that it surrounds the required objects.
I then accessed the “Render to Texture” options, using the above settings. Most importantly ensuring the “projection mapping” is enabled, and setting the output to have one Diffuse Map and one Normal Map. Once happy, it was time to render.
Once baked, I was presented with a diffuse and normal map. Next, I exported the left image to Adobe Photoshop to create an Alpha Channel. First, sourcing a metal texture which would be used as the diffuse map.
The chosen texture is to be set as my only layer, cutting and pasting the initial mesh image from the background into the “Alpha 1” layer under the channels tab. The result is shown below.
This was then exported as a “Tiff” file, or a file format which supports transparency. I then returned to 3DS Max, ready to apply these textures upon a model.
Within the material editor, I began compiled the final texture, applying my new created files as shown above.
Diffuse Colour – Will provide the metal mesh texure and shape.
Specular Level – As the model is metallic, this will provide a slight reflectiveness to the texture.
Opacity – With the Alpha Channel applied, this will make the gaps in the mesh transparent, unseen to the audience.
Bump – Using the Normal Map, this will bring out detail in the texture, making the model appear more 3D.
I then applied this finalised texture upon a square plane I had created. The result is shown below.
To conclude, I applied the method in combination with a the fence model to be used within our game. The final model has less than 200 polygons, achieving the result I set out to gain.