In this tutorial, I am going to show how to use Alpha or Opacity maps within 3ds max.
Alpha or opacity maps are frequently used in games. Game engines can’t handle too much polygons so let’s say if we have to create a tree for some real time stuff then instead of creating each and every leaf, we will use a leaf diffuse with it’s alpha map.
Working of Alpha or Opacity maps
Here is a simple image showing the effects of two types of Alpha images and their results
So, the above case clears that we should use those images in which Black should be 100% black and White should be 100% White, we can’t use gray shaded images (the “in-betweens” colors of Black and White) as our Alpha or Opacity maps.
To demonstrate how the Alpha maps work, I am using a seamless chain link fence texture (Learn more about tileable / seamless textures : Method 1, Method 2). In order to use this texture in 3ds max we should have it’s alpha image so let’s start with creating the alpha or opacity map of our chain link fence texture.
We have to select our chain link first so, Ctrl + click on the chain link layer’s thumbnail to select the image. Our image has no background so it will select the image pixels only while the transparent pixels remain unselected.
Now, create a new layer and name it as Alpha or Opacity map. Now with the Alpha layer selected, fill your selection with White color.
Now, inverse the selection by pressing Ctrl + Shift + I on your keyboard and fill it with Black color. Save your texture as chain_link_diffuse and the alpha as chain_link_alpha. I am using PSD file format for my files but you can also use other image file formats like JPEG or TGA.
Now, let’s use our maps in 3ds max so, first create a simple Plane geometry then open up the Material Editor (M). Select a material slot and under Maps rollout (same under Blinn Basic Parameters rollout), click on the Diffuse Color button. Now, choose Bitmap from the list and load the chain link texture that we just created. After loading your chain link texture from the location, just click on Go to Parent button, it will bring you back to the place where you were before. Apply the material to the plane geometry and click on the Show Standard Map in Viewport Now, notice how our texture looks without it’s Alpha image.
Note: Under Shader Basic Parameters rollout just turn on 2-Sided option so that the texture will display on the both sides of the geometry and do not return the black surface during render.
Now, again under the Maps rollout, click on Opacity button and load the Alpha map that we made for our chain link texture. Now, the texture looks perfect with it’s alpha or opacity map.
We have one more thing to fix, that is, the tiling of the texture so, select the plane geometry and apply the UVW Map modifier to it. Now, select the gizmo and scale it according to your convenience and you are done.
You can use this technique to create low poly foliage, tree leaves, character hair etc. for your games and enviornments. I hope you enjoyed this one. Let me know if you face any problem following this tutorial. Good Luck.