I want to have a few varieties of foliage in my level, so I've started work on a second tree-type. I'm going to allow this one to be a little higher in poly count (under 2000 triangles) as there will be fewer of this type used in the level. This type will also be placed more 'closely' to where the player will be roaming, as opposed to the first tree type which I will use to create a woody area around the outskirts of the level.
I've tried out a different shape for the leaf plane which I've noticed being used in some examples of low poly tree models I looked at online. It's more like a curved plane which recreates the appearance of how a real-life tree's leaves form in sections.
I have had to duplicate each of these planes, with one sitting very closely underneath the other and the normals reversed because in Unity, only the face normals appear visible - the other side of the faces are invisible. After a quick test with my previous tree in Unity I noticed that at some angles the tree branches appeared bare, but with the doubled planes technique, the leaf textures are visible at all angles.
In Photoshop I've painted two variants of a copper birch tree leaf. I decided to go for a red/purple hue like one I tested in my concept art from pre-production, I think it will be an interesting contrast to the turquoise and greens that dominate the rest of the level.
This is the finished tertiary branch texture, each leaf was originally on a separate layer so that I could alter the hues and brightness of a selection of leaves in order to give the branch some variety. I created two variants of this texture too, so that the tree should look a little more natural.
This shows how I've built up layers of leaf planes from the lower branches upwards.
The almost fully-filled tree.
After the poly count exceeded 2k triangles, I decided that I would need to change the mesh of the leaf plane in order to halve the number of triangles. Now the tree is just over 1500 triangles.
The tree model (not yet with textures or a skybox) in Unity. Once the normal maps are sorted it will start to look a little more solid.
