Performance Optimization
Optimizing Graphics Performance
Optimizing Graphics Performance
Why is graphics performance low?
Optimizing Graphics Performance
Why is graphics performance low? Fillrate? (screen pixels * overdraw)
Optimizing Graphics Performance
Why is graphics performance low? Fillrate? (screen pixels * overdraw) Shader computations?
Optimizing Graphics Performance
Why is graphics performance low? Fillrate? (screen pixels * overdraw) Shader computations? Vertex count? (Intel GMA950)
Optimizing Graphics Performance
Why is graphics performance low? Fillrate? (screen pixels * overdraw) Shader computations? Vertex count? (Intel GMA950) Draw calls?
Draw calls
Draw calls
Lots of objects tax the CPU. On the other
hand lots of Triangles tax the GPU.
Draw calls
Lots of objects tax the CPU. On the other
hand lots of Triangles tax the GPU.
You still need the CPU for game code
Draw calls
Lots of objects tax the CPU. On the other
hand lots of Triangles tax the GPU.
You still need the CPU for game code On a modern machine you can use around
500 draw calls per frame
Draw calls
Lots of objects tax the CPU. On the other
hand lots of Triangles tax the GPU.
You still need the CPU for game code On a modern machine you can use around
500 draw calls per frame
Each pixel light renders a mesh one more
time. Dont use too many pixel lights!
Combining
Combining
Lots of objects in the scene - bad.
Combining
Lots of objects in the scene - bad. Spatially close objects combined - good.
Combining
Lots of objects in the scene - bad. Spatially close objects combined - good. Overcombined objects - bad again.
No Combining
No Combining
Lots of objects
No Combining
Lots of objects High draw count
No Combining
Lots of objects High draw count Bad on CPU and GPU
Good Combining
Good Combining
Combined objects are close to each other
and use the same material.
Good Combining
Combined objects are close to each other
and use the same material.
E.g. combine inside rooms of the house.
Good Combining
Combined objects are close to each other
and use the same material.
E.g. combine inside rooms of the house. Often requires using texture sheets!
Good Combining
Combined objects are close to each other
and use the same material.
E.g. combine inside rooms of the house. Often requires using texture sheets! Rule of thumb: object size and point/spot
light size about the same.
Bad Combining
Bad Combining
Never combine objects that are far apart!
Bad Combining
Never combine objects that are far apart! If light shines only on part of object, whole
object needs to be drawn.
Bad Combining
Never combine objects that are far apart! If light shines only on part of object, whole
object needs to be drawn.
If camera sees only a tiny corner of object,
whole object needs to be drawn.
Combining Demo
Combining Demo
How much do I actually gain?
Combining Demo
How much do I actually gain? Can your game afford not combining? Can
you afford a factor 30x in the worst case?
Combining Demo
How much do I actually gain? Can your game afford not combining? Can
you afford a factor 30x in the worst case?
Geometry matches lighting
Lights are for?
Lights are for?
Dynamic lights!
Lights are for?
Dynamic lights! Lightmapping to the rescue
Lights are for?
Dynamic lights! Lightmapping to the rescue Combine the two. Lightmap your scene to
get rid of all static lights. Its faster and looks better!
Lights are for?
Dynamic lights! Lightmapping to the rescue Combine the two. Lightmap your scene to
get rid of all static lights. Its faster and looks better! dynamic shadows
When to use lights? Rockets, torches and
Lights are for?
Dynamic lights! Lightmapping to the rescue Combine the two. Lightmap your scene to
get rid of all static lights. Its faster and looks better! dynamic shadows
When to use lights? Rockets, torches and Culling masks!
How to lightmap?
How to lightmap?
Lightmapping is done in Maya or other
rendering Tools.
How to lightmap?
Lightmapping is done in Maya or other
rendering Tools.
Easily imported into Unity, simply switch to
any lightmapped shader
How to lightmap?
Lightmapping is done in Maya or other
rendering Tools.
Easily imported into Unity, simply switch to
any lightmapped shader
Ask Ethan, our Maya expert! Hell happily
get you up to speed with Lightmapping in Maya. Use the sign up sheet!
Avert Fate Demo
Optimizing Script code
Be aware of expensive functions
Be aware of expensive functions
A lot of Utility functions may be slow.
Be aware of expensive functions
A lot of Utility functions may be slow. So while useful and sometimes necessary.
avoid it.
Raycasting
Raycasting
Raycasting against Meshes is slow. Dont do
a lot of raycasts each frame
Raycasting
Raycasting against Meshes is slow. Dont do
a lot of raycasts each frame
Use culling mask to early out raycasting
Raycasting
Raycasting against Meshes is slow. Dont do
a lot of raycasts each frame
Use culling mask to early out raycasting Raycast only every third frame?
Finding objects
Finding objects
FindObjectsOfType, FindGameObjectWithTag,
GameObject.Find
Finding objects
FindObjectsOfType, FindGameObjectWithTag,
GameObject.Find
Avoid doing it too much. Its convenient but
those calls can quickly add up
Finding objects
FindObjectsOfType, FindGameObjectWithTag,
GameObject.Find
Avoid doing it too much. Its convenient but
those calls can quickly add up
Use static variable
Finding objects
FindObjectsOfType, FindGameObjectWithTag,
GameObject.Find
Avoid doing it too much. Its convenient but
those calls can quickly add up
Use static variable Store all active components of a type using a
static ArrayList and OnEnable / OnDisable
Only Update nearby objects
Only Update nearby objects
Dont run scripts at all, when far away
Only Update nearby objects
Dont run scripts at all, when far away function Update () { if (far away) return; }
does NOT count. Use enabled = false;
Only Update nearby objects
Dont run scripts at all, when far away function Update () { if (far away) return; }
does NOT count. Use enabled = false;
Use triggers for nding out when player is
close by or use coroutine that updates every 5 seconds
Math
Math
Add, subtract, multiply: a couple cycles
Math
Add, subtract, multiply: a couple cycles Divide: 30-40 cycles
Math
Add, subtract, multiply: a couple cycles Divide: 30-40 cycles Square root, sin, cos: 60-100 cycles
Sqrt and Normalize
Sqrt and Normalize
In inner loops avoid Sqrt and Normalize.
They are fairly expensive. (Normalize internally uses Sqrt)
Sqrt and Normalize
In inner loops avoid Sqrt and Normalize.
They are fairly expensive. (Normalize internally uses Sqrt) +vec.z ); Use sqrMagnitude instead.
Normalize = vec / Sqrt (vec.x+ vec.y
Sqrt and Normalize
In inner loops avoid Sqrt and Normalize.
They are fairly expensive. (Normalize internally uses Sqrt) +vec.z ); Use sqrMagnitude instead.
Normalize = vec / Sqrt (vec.x+ vec.y if (distance > dif.magnitude) Bad!
Sqrt and Normalize
In inner loops avoid Sqrt and Normalize.
They are fairly expensive. (Normalize internally uses Sqrt) +vec.z ); Use sqrMagnitude instead.
Normalize = vec / Sqrt (vec.x+ vec.y if (distance > dif.magnitude) Bad! if (distance * distance > dif.sqrMagnitude)
Cache
Cache
Cache hit: a couple cycles
Cache
Cache hit: a couple cycles Cache miss: 40-hundreds of cycles
Cache
Cache hit: a couple cycles Cache miss: 40-hundreds of cycles What does a simple transform.position do
internally?
Cache
Cache hit: a couple cycles Cache miss: 40-hundreds of cycles What does a simple transform.position do
internally?
Walk memory linearly (Structs)
JavaScript
JavaScript
Dynamic typing is slow!
JavaScript
Dynamic typing is slow! Static typing gives you the same
performance as C#
JavaScript
Dynamic typing is slow! Static typing gives you the same
performance as C#
50% the performance of optimized C++
code. 20x faster than Mozilla JavaScript
JavaScript
Dynamic typing is slow! Static typing gives you the same
performance as C#
50% the performance of optimized C++
code. 20x faster than Mozilla JavaScript
#pragma strict to the rescue
Demo Boids
Questions?
