Just like on PCs, mobile platforms like iOSApple’s mobile operating system. More info
See in Glossary and Android have devices of various levels of performance. You can easily find a phone that’s 10x more powerful for renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
See in Glossary than some other phone.
Quite easy way of scaling:
Graphics performance is bound by fillrate, pixelThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
See in Glossary and geometric complexity (vertex count). All three of these can be reduced if you can find a way to cull more renderers. Occlusion cullingA Unity feature that disables rendering of objects when they are not currently seen by the camera because they are obscured (occluded) by other objects. More info
See in Glossary could help here as Unity will automatically cull objects outside the viewing frustum.
On mobiles you’re essentially fillrate bound (fillrate = screen pixels * shader complexity * overdraw), and over-complex shadersA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
See in Glossary is the most common cause of problems. So use mobile shaders that come with Unity or design your own but make them as simple as possible. If possible simplify your pixel shaders by moving code to vertex shaderA program that runs on each vertex of a 3D model when the model is being rendered. More info
See in Glossary.
If reducing the Texture Quality in Quality settings makes the game run faster, you are probably limited by memory bandwidth. So compress textures, use mipmaps, reduce texture size, etc.
LOD (Level of Detail) - make objects simpler or eliminate them completely as they move further away.
Mobile GPUs have huge constraints in how much heat they produce, how much power they use, and how large or noisy they can be. So compared to the desktop parts, mobile GPUs have way less bandwidth, low ALU performance and texturing power. The architectures of the GPUs are also tuned to use as little bandwidth & power as possible.
Unity is optimized for OpenGL ES 2.0, it uses GLSL ES (similar to HLSL) shading language. Built in shaders are most often written in HLSL (also known as Cg). This is cross compiled into GLSL ES for mobile platforms. You can also write GLSL directly if you want to, but doing that limits you to OpenGL-like platforms (e.g. mobile + Mac) since there currently are no GLSL->HLSL translation tools. When you use float/half/fixed types in HLSL, they end up highp/mediump/lowp precision qualifiers in GLSL ES.
Here is the checklist for good practice:
void Update (){
// flip between meshes
bufferMesh = on ? meshA : meshB;
on = !on;
bufferMesh.vertices = vertices; // modification to mesh
meshFilter.sharedMesh = bufferMesh;
}
Checking if you are fillrate-bound is easy: does the game run faster if you decrease the display resolution? If yes, you are limited by fillrate.
Try reducing shader complexity by the following methods:
It is often the case that games are limited by the GPU on pixel processing. So they end up having unused CPU power, especially on multicore mobile CPUs. So it is often sensible to pull some work off the GPU and put it onto the CPU instead (Unity does all of these): meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary skinningThe process of binding bone joints to the vertices of a character’s mesh or ‘skin’. Performed with an external tool, such as Blender or Autodesk Maya. More info
See in Glossary, batching of small objects, particle geometry updates.
These should be used with care, not blindly. If you are not bound by draw calls, then batching is actually worse for performance, as it makes culling less efficient and makes more objects affected by lights!
Physics can be CPU heavy. It can be profiled via the Editor profilerA window that helps you to optimize your game. It shows how much time is spent in the various areas of your game. For example, it can report the percentage of time spent rendering, animating or in your game logic. More info
See in Glossary. If Physics appears to take too much time on CPU:
These are the popular mobile architectures. This is both different hardware vendors than in PC/console space, and very different GPU architectures than the “usual” GPUs.
Spend some time looking into different rendering approaches and design your game accordingly. Pay especial attention to sorting. Define the lowest end supported devices early in the dev cycle. Test on them with the profiler on as you design your game.
Use platform specific texture compressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
See in Glossary.
Only PowerVR architecture (tile based deferred) to be concerned about.
This means:
And cons:
Downloads are implemented via async API provided by OS, so OS decides how many threads need to be created for downloads. When launching multiple concurrent downloads you should keep in mind total device bandwidth it can support and amount of free memory. Each concurrent download allocates its own temporal buffer, so you should be careful there to not run out of memory.
Sometimes there’s nothing in the console, just a random crash