Memory Conservation tips for Unity

MemoryTips.cs

// Let's talk about memory conservation
// If a Unity API returns an array, it allocates a new copy. 
// Every time it is accessed, Even if the values do not change.

// Bad Sample 1: this code allocate too many Arrays
for ( int i = 0;i < Input.touches.Length; i++ ) // Get() accessor call + creating copy
{
 Touch touch = Input.touches[i]; // Creating copy
 // …
}

// Good sample: this only allocates one copy of Touch array in memory
Touch[] touches = Input.touches;
for ( int i = 0; i < touches.Length; i++ )
{
 Touch touch = touches[i];
 // …
}

// Very Good sample: using Allocationless API, zero.
int touchCount = Input.touchCount;
for ( int i = 0; i < touchCount; i++ )
{
 Touch touch = Input.GetTouch(i);
 // …
}

// Material / Animation / Shader searches by string: BAD
// Never address Material, Shader, or Animator properties by name.
// Internally, hashes the property name into an integer. 

// Don't do this
void SetMaterial(){
  material.SetColor(“_Color”, Color.white);
  animator.SetTrigger(“attack”);
}

// but instead, cache them into integers at startup
static readonly int material_Color = Shader.PropertyToID(“_Color”);
static readonly int anim_Attack = Animator.StringToHash(“attack”); 

void SetMaterialFast(){
  material.SetColor(material_Color, Color.white);
  animator.SetTrigger(anim_Attack);
}


/// GET() / SET() problems
// Look at this snippet
int Accum{ get;	set;}
Accum = 0;	
for(int i = 0; i < myList.Count; i++) {	 // you are internally calling List::get_Count every iteration
    Accum += myList[i];	 // List::get_Value,get_Accum and set_Accum is called every iteration 
}

// over 100 000 elements: 324 milliseconds

// now look at this, only one call
int accum = 0;	
int len = myList.Count;	
for(int i = 0;i	< len; i++) {	
    accum += myList[i];  // List::get_Value	
}
// over 100 000 elements: 128 milliseconds, near 3 times faster