COMP30019-Project-1

Project 1 for 2018 Semester 2 of COMP30019 Graphics & Interaction
Contributors:
Alexander Terp
Samuel Xu

Method

We utilize procedural meshes in the implementation of our terrain. The steps for our project is as follows:

1. Get/create a Mesh object (part of MeshFilter) for the terrain object.
2. Calculate a (2^n + 1) by (2^n + 1) 2D float[,] array using the Diamond-Square algorithm, each float corresponding to a height.
3. Generate ((2^n + 1) * (2^n + 1)) vertices row by row, each spaced correctly. Assign the corresponding heights from the aforementioned float[,] array.
4. Set the mesh triangles properly, row by row.
5. Utilize in-built Unity methods to calculate mesh normals and a mesh collider.
6. Calculate the lowest and highest points on the terrain using the aforementioned float[,] heights array.
7. Generate a procedural mesh for the water using a sufficient number of vertices and a similar method as generating the terrain's mesh (except no heights).
8. Add a mesh collider to the water.
9. Set the height of the water to be the midpoint between the highest and lowest points on the terrain. This ensures water and land is always visible each generation.
10. Set the colors of vertices on the terrain. This involves taking into account the height of the water to determine the level of sand, as well as taking into account the highest point to determine a level for snow. From here, the rest of the colors of mountain and grass are interpolated.

We then utilize a custom shader that performs Phong illumination and shading while also rendering the colors of the vertices to give the terrain height-based coloration.

Waves shader:

Additionally, we utilize a custom shader for the waves. This shader implements Gerstner-style waves and contains two octaves i.e. large waves (named in our project as "tides") and small waves on top of each other. This was calculated with a sin function on the y axis, and a cos function on the x axis, which sum together to produce a wave 'rolling' motion. This smaller wave is then combined with a wave direction vector, which allows the user to input a direction for the wave. Vertices are displaced in the shader and not in a script, as specified.

Terrain resolution:

The terrain, on default, has n set to equal 7 i.e. it has a total of (2^7 + 1)^2 = 16,641 vertices. The max that a single mesh in Unity allows is around 65,000. However, if we increase n to 8, we get (2^8 + 1)^2 = 66,049 vertices, which is slightly over the limit. This causes some artifacting, and so we limit n to be [1, 7].

Camera:

The camera has been implemented as specified. The user can intuitively pitch, yaw, and move with the WASD keys. They are bounded within the dimensions of the terrain utilizing a simple clamping method. We have also attached a sphere collider to the camera to prevent the user from going underground (recall that both the terrain and water has mesh colliders). The camera's collider is set to Continuous collision detection to prevent tunneling, which would be possible if the user tried to "sprint" (see "Extras" section) perpendicularly to the water or terrain and it was set to discrete.

Lighting / day/night cycle:

We've implemented a full day/night cycle using two directional lights. The sun and moon are modeled by flattened spheres, and the night stars are generated via a particle system. As time progresses, these rotate, and lighting is changed accordingly as well. Additional details about the day/night cycle addressed in the "Extras" section.

Performance / FPS Lock

The simulation runs well on the devices we have developed on. Below are some benchmarks for our developer devices:
Desktop @ 1080p: i7-3930K, AMD Radeon HD 7950, 8 GB DDR3 RAM: 110 FPS average
Desktop @ 1080p: i7-6800K, Nvidia GTX 1080 Ti, 32 GB DDR4 RAM: 80 FPS average
Laptop @ 720p: i5-3437U, Intel HD Graphics 4000, 8 GB DDR3 RAM: 50 FPS average
Laptop @ 1080p: i5-7300U, Intel HD Graphics 620, 8 GB DDR4 RAM: 85 FPS average

However, the lab computers that the simulation is supposed to run on perform far worse. That's to be expected as they are only able to run a completely empty Unity scene at an average FPS of 60. Because we are concerned with the performance on weaker devices, we decided to lock our application to 40 FPS to maintain a consistent FPS as required in the spec. We believe 40 to be a fair compromise between usability and required computer power.

Extras:

We enjoyed the project so much that we wanted to add some additional features, some of which affected the specified features in some way.

• We implemented the ability to "sprint" with left shift, which goes 12x normal speed.
• We implemented UI system that lets the user tweak values in the simulation, such as terrain generated parameters, wave parameters, coloring parameters, time, fov, etc.
• We implemented an in-game time clock. This clock goes from 0 seconds to 86399 seconds, or 11:59:59 PM, before ticking over and wrapping back to 0. The aforementioned /night cycle is tied to this clock, which goes at real time. This means that, if left at default speed, it'd take 24 real hours to simulate a day/night cycle. However, both the time and time speed can be set in the top left of the UI. Also, the waves are tied to this in-game clock. Therefore, if you speed up time, the oscillation of the waves speed up too.

Disclaimers:

Water texture provided by SimplyBackgrounds @ Deviant Art
https://www.deviantart.com/simplybackgrounds/art/Water-Texture-49283686