Once you have a large game, with many large 3D models, you will probably start to wonder about the speed and memory usage.
The main tool to measure your game speed is the Frames Per Second (FPS) value. Use the TCastleControlBase.Fps or TCastleWindowBase.Fps to get an instance of TFramesPerSecond. It contains two useful numbers (and some extra information): TFramesPerSecond.RealFps and TFramesPerSecond.OnlyRenderFps.
You can display the
Window.Fps.ToString value in any way you like.
If you use
TCastleWindow, you can trivially turn on
You can display FPS using
TCastleLabel. See the manual page about using our user-interface classes. Just update the
TCastleLabel.Caption in every
OnUpdate event to show the current FPS value. An an example, create a new project using CGE editor — all new project templates include an FPS counter.
Or you can display FPS using
TCastleFont.Print in every
Render event. See the manual about custom drawing. As an example, see how examples/physics/physics_3d_demo/gameinitialize.pas shows the FPS (search for
You can show the FPS value on some LCL label or form caption (if you use LCL forms).
Warning: do not change the Lazarus control too often (like every frame).
Updating normal Lazarus controls all
the time may slow your OpenGL context drastically.
Also, do not write to the console (e.g. using
every frame — the very fact of doing this will slow down your application a lot.
If you need to change some Lazarus control,
or write the FPS to some log, use a timer
(like TCastleTimer or
TTimer) to write it e.g. only once per second.
are actually just an average from the last second,
so there's really no need to show them more often.
There are two FPS numbers measured: "real FPS" and "only render FPS". "Only render FPS" is usually slightly larger. Larger is better, of course: it means that you have smoother animation.
Use "real FPS" to measure your overall game speed. This is the actual number of frames per second that we managed to display.
Make sure to have an animation that constantly updates your
screen, or use
(it is the default since CGE 6.0, so you're probably already set).
Otherwise, we may not refresh the screen continuously (no point to
redraw, if both the scene and camera are completely static; this way we let
other applications to work more smoothly, and we save your laptop battery).
Then "real FPS" will drop to almost zero. This can be detected by looking at
Window.Fps.WasSleeping. The output of
also accounts for it, showing "no frames rendered"
or "no need to render all frames".
If you hope to see higher values than 100 (the default
LimitFPS value) then turn off "limit FPS" feature.
TCastleWindow(if you use a standard program template, or manually call
Window.ParseParameters) you can do it just by passing
You will also need to turn off "vertical synchronization" of the GPU to achieve arbitrarily high FPS.
Note that the monitor will actually drop some frames above it's frequency, like 60. (This is relevant only if "vertical synchronization" is off.)
This may cause you to observe that above some threshold, FPS are "easier to gain" by optimizations, which may lead you to a false judgement about which optimizations are more useful than others. To make a good judgement about what is faster / slower, compare two versions of your program when only one thing changes.
"Only render FPS" measures how much frames we
would get, if we ignore the time spent outside
It's useful to compare it with "real FPS",
large difference may indicate that you can make some optimizations
in CPU code (e.g. collision detection or animations) to gain overall speed.
Modern GPUs work in parallel to the CPU. So "how much time CPU spent in Render" doesn't necessarily relate to "how much time GPU spent on performing your drawing commands".
For example: if you set
LimitFPS to a small value (like 10),
you may observe
that "only render FPS" grows very high. Why? Because when the CPU is idle
(which is often if
LimitFPS is small), then GPU has a free time to
finish rendering previous frame. So the GPU does the work for free,
Render time, when your CPU is busy waiting.
OTOH when CPU works on producing new frames all the time, then you have to
Render until previous frame finishes.
In other words, improvements to "only render FPS" must be taken with a
grain of salt. We spend less or more time in
this does not always mean that we render more efficiently.
Still, "only render FPS" is often a useful indicator.
It means that
Render is quick.
So we probably don't need to wait for the whole previous frame to finish
when starting rendering a new frame. To some extent, that's good —
you're probably doing useful work in the meantime on CPU, while GPU is working.
Often it means that there is something to gain optimizing the CPU side,
like collisions or animations.
No guarantees: It does not mean that you can actually achieve this number of FPS as "real FPS". At some point, decreasing CPU work will just uncover that we have to wait for GPU to finish anyway. In which case, you will observe "only render FPS" to drop (which is nothing alarming, it doesn't necessarily mean that rendering is less efficient; it just means that GPU speed becomes a factor too).
Then we spend most time in
This is normal if neither rendering nor collisions are a bottleneck
— then we probably just spend time in the
for vertical synchronization to happen, and you can't really achieve more
than 60 real FPS in the typical case with "vertical synchronization"
However, if your "real FPS" is much lower than your refresh rate, and your "only render FPS" is equal to "real FPS", then you probably can optimize the rendering. (Make smaller models, use less demanding shader effects etc.)
Another useful statistics to display is Viewport.Statistics.ToString. This shows how many scenes, and how many shapes, have been rendered in the last frame. It can be a useful guideline when to activate some specific optimizations discussed below. E.g. large value of displayed shapes may indicate that dynamic batching may be useful.
First of all, watch the number of vertexes and faces of the models you load. Use view3dscene menu item Help -> Scene Information for this.
Graphic effects dealing with dynamic and detailed lighting, like shadows or bump mapping, have a cost. So use them only if necessary. In case of static scenes, try to "bake" such lighting effects to regular textures (use e.g. Blender Bake functionality), instead of activating a costly runtime effect.
When you're in the middle of the development and you're testing the game for bugs,
that adds a lot of run-time checks to your code. This allows to get
a clear and nice error when you e.g. access an invalid array index.
If you use our
just pass the
--mode=debug command-line parameter to it.
Our vectors are also like arrays, so doing stuff like
MyVector := 123.0;
is also checked (it's valid if
MyVector is a 3D or 4D vector, invalid if it's a 2D vector).
Actually, this simple case is checked at compile-time with the new vector API
in Castle Game Engine 6.3,
but more convoluted cases are still checked at run-time.
When you need the maximum speed (when you want to build a "final"
version for the player, or when you check / compare / profile the speed),
always use the
The code runs much faster in release mode. The speed difference may be really noticeable. For example, as of Castle Game Engine 6.3, our "toy" software ray-tracer (CastleRayTracer unit) is 1.9 times slower in development mode vs release mode. The speed differences of a typical game are usually not that drastic (since a normal game doesn't spend 100% of time calculating math expressions on CPU, unlike a software ray-tracer), but significant differences are still expected, especially if you measure the performance of a particular calculation (not just looking at game FPS).
So in most cases it's really important that you measure the speed only of the release build of your game, and this is the version that you want to provide to your players.
If the player can see the geometry faces only from one side,
then backface culling should be on.
This is the default case (X3D nodes like
solid field equal
TRUE by default).
It avoids useless drawing of the other side of the faces.
Optimize textures to increase the speed and lower GPU memory usage:
Appearanceacross many X3D shapes, if possible). This avoids texture switching when rendering, so the scene renders faster. When exporting from Spine, be sure to use atlases.
TSpriteclass) instead of separate images (like
TGLVideo2Dclass). This again avoids texture switching when rendering, making the scene render faster. It also allows to easily use any texture size (not necessarily a power of two) for the frame size, and still compress the whole sprite, so it cooperates well with texture compression.
TextureProperties.anisotropicDegreeif not needed.
anisotropicDegreeshould only be set to values > 1 when it makes a visual difference in your case.
There are some
TCastleScene features that are usually turned on,
but in some special cases may be avoided:
ProcessEventsif the scene should remain static.
Scene.Spatialif you don't need better collisions than versus scene bounding box.
Scene.Spatialif the scene is always small on the screen, and so it's usually either completely visible or invisible.
ssRenderingadds frustum culling per-shape.
Various techniques to optimize animations include:
If your model has animations but is often not visible (outside
of view frustum), then consider using
Scene.AnimateOnlyWhenVisible := true
If the model is small, and not updating it's animations every frame will not be noticeable, then consider setting
to something larger than 0 (try 1 or 2).
For some games, turning globally
OptimizeExtensiveTransformations := true improves the speed. This works best when you animate multiple
Transform nodes within every X3D scene, and some of these animated
Transform nodes are children of other animated
Transform nodes. A typical example is a skeleton animation, for example from Spine, with non-trivial bone hierarchy, and with multiple bones changing position and rotation every frame.
In a similar scenario, activating InternalFastTransformUpdate may be also beneficial. We plan to make this optimization automatic in the future.
Watch out what you're changing in the X3D nodes. Most changes, in particular the ones that can be achieved by sending X3D events (these changes are kind of "suggested by the X3D standard" to be optimized) are fast. But some changes are very slow, cause rebuilding of scene structures, e.g. reorganizing X3D node hierarchy. So avoid doing it during game. To detect this, set
LogSceneChanges := true and watch log (see manual chapter "Logging") for lines saying "ChangedAll" - these are costly rebuilds, avoid them during the game!
Using Physically Based Rendering (through X3D
default when loading glTF) has a cost.
If you can, use instead
Phong lighting model (through X3D
for glTF, set GltfForcePhongMaterials).
Moreover, use Gouraud shading, if you can. This is actually the default for Phong lighting, unless you request bump mapping, shadow maps or other fancy stuff.
When designing lights, limit their scope or radius. When creating lights in new Blender, select "Custom Distance" at light. This limits the shapes where the light has to be taken into account.
Modern GPUs can "consume" a huge number of vertexes very fast, as long as they are provided to them in a single "batch" or "draw call".
In our engine, the "shape" is the unit of information we provide to GPU. It is simply a VRML/X3D shape. In most cases, it also corresponds to the 3D object you design in your 3D modeler, e.g. Blender 3D object in simple cases is exported to a single VRML/X3D shape (although it may be split into a couple of shapes if you use different materials/textures on it, as VRML/X3D is a little more limited (and also more GPU friendly)).
The general advice is to compromise:
Do not make too many too trivial shapes. Do not make millions of shapes with only a few vertexes — each shape will be provided in a separate VBO to OpenGL, which isn't very efficient.
Do not make too few shapes. Each shape is passed as a whole to OpenGL (splitting shape on the fly would cause unacceptable slowdown), and shapes may be culled using frustum culling or occlusion queries. By using only a few very large shapes, you make this culling worthless.
A rule of thumb is to keep your number of shapes in a scene between 100 and 1000. But that's really just a rule of thumb, different level designs will definitely have different considerations.
You can also look at the number of triangles in your shape. Only a few triangles for a shape is not optimal — we will waste resources by creating a lot of VBOs, each with only a few triangles (the engine cannot yet combine the shapes automatically). Instead, merge your shapes — to have hundreds or thousands of triangles in a single shape.
If you have a large number of small shapes using the same shader, consider turning on DynamicBatching. This will internallly detect and merge multiple shapes into one just before passing them to the GPU. In some cases, it is a very powerful optimization, reducing the number of draw calls.
Viewport.Statistics.ToString to see whether it reduces the number
of rendered shapes.
It is particularly useful e.g. to optimize Spine rendering, as 2D animated models are often composed from a number of trivial textured quads that are transformed each frame. Dynamic batching can drastically reduce the number of draw calls in this case.
To reduce memory usage, you can use the same TCastleScene instance many times within
Viewport.Items, usually wrapped in a different TCastleTransform. The whole code is ready for such "multiple uses" of a single scene instance.
For an example of this approach, see frogger3d game (in particular, it's main unit game.pas). The game adds hundreds of 3D objects to
Viewport.Items, but there are only three
TCastleScene instances (player, cylinder and level).
However, this optimization is suitable only if all the visible scenes (that are actually a single TCastleScene instance) are always in the same animation frame (or maybe they are not animated at all). If you want to play different animations, you have to create separate TCastleScene instances (you can create them efficiently using the TCastleScene.Clone method).
In some cases, combining many
TCastleScene instances into one helps. To do this, load your 3D models to
LoadNode, and then create a new single
TX3DRootNode instance that will have many other nodes as children. That is, create one new
TX3DRootNode to keep them all, and for each scene add it's
TX3DRootNode (wrapped in
TTransformNode) to that single
This allows you to load multiple 3D files into a single
TCastleScene, which may make stuff faster — there will be only one octree (used for collision routines and frustum culling) for the whole scene. Right now, we have an octree inside each TCastleScene, so it's not optimal to have thousands of TCastleScene instances with collision detection.
See the manual page Transformation hierarchy for a detailed discussion of this, and when it may be a good idea to merge scenes.
Note that we do not advise using this optimization too hastily. It sometimes makes sense, but usually having one TCastleScene for each one model (that is, not combining them) is better:
It makes code simpler. You trivially load each model by
TCastleScene.Load. You don't need to deal or understand anything about X3D nodes.
It allows to run animations in the most intuitive way: on each model, you can call
The physics engine right now treats an entrie TCastleScene as a single rigid body. You cannot combine two scenes, if you want them to be independent rigid bodies for the physics engine.
Various things discussed here are planned to be improved in the engine, to avoid leaving you with such difficult decision. On one side, we plan to merge the
TTransformNode hierarchies, making the gain from merging scenes irrelevant. On the other hand, we plan to allow physics to treat specific shapes as rigid bodies, making it possible to apply physics on smaller units than "entire TCastleScene".
If you include
TCastleScene.Spatial, then we build a spatial structure (octree)
that performs collisions with the actual triangles of your 3D model.
This results in very precise collisions, but it can eat an unnecessary
amount of memory (and, sometimes, take unnecessary amount of time)
if you have a high-poly mesh.
Often, many shapes don't need to have such precise collisions
(e.g. a complicate 3D tree may be approximated using a simple cylinder
representing tree trunk).
Collision node to mark some shapes as
non-collidable or to provide a simpler "proxy" shape to use for
collisions. Right now, using the
writing X3D code manually, but it's really trivial. You can
still export your scenes from 3D software, like Blender —
you only need to manually write a "wrapper" X3D file around them.
vrml_2/collisions_final.wrldemo inside our demo VRML/X3D models.
You can also build a
Collision node by code.
We have a helper method for this: TCollisionNode.CollideAsBox.
Another possible octree optimization is to adjust the parameters how the octree is created. You can set octree parameters in VRML/X3D file or by ObjectPascal code. Although in practice I usually find that the default values are really good.
Avoid any loading (from disk to normal memory, or from normal memory to GPU memory) once the game is running. Doing this during the game will inevitably cause a small stutter, which breaks the smoothness of the gameplay. Everything necessary should be loaded at the beginning, possibly while showing some "loading..." screen to the user.
TCastleViewport.PrepareResources to load everything referenced by your scenes to GPU. Be sure to pass all the
TCastleScene instances to
TCastleViewport.PrepareResources in the "loading" stage.
Enable some (or all) of these flags to get extensive information in the log about all the loading that is happening:
WritelnLog(Profiler.Summary)is a great way to be informed about most loading.
Beware: Some of these flags (in particular
LogAllLoading) can produce a lot of information, and you probably don't want to see it always. Dumping this information to the log will often cause a noticeable slowdown during loading stage, so do not bother to measure your loading speed when any of these flags are turned on. Use these flags only to detect if something "fishy" is happening during the gameplay.
You can also use TCastleProfiler to easily get information about what was loaded, and what took most time to load.
The engine by default performs frustum culling, using per-shape
and per-scene bounding boxes and spheres. If you add
flag to the
Scene.Spatial, this will be even faster thanks
to using shapes octree.
Using the hardware occlusion query is often a good idea
in large city or indoor levels,
where walls or large buildings can obscure a significant part of your geometry.
Activate it by simply turnnig on the flag
Scene.Attributes.UseOcclusionQuery := true.
Note that our simple implementation may sometimes show a lag of 1 frame
when the object is not rendered, but it should be.
You can also cull objects based on their distance from the camera,
examples/3d_rendering_processing/fog_culling.lpr for example.
This is a natural optimization when you have a heavy fog.
We use alpha blending to render partially transparent
shapes. Blending is used automatically if you have a texture with
a smooth alpha channel, or if your
is less than 1.
Note: Just because your texture has some alpha channel,
it doesn't mean that we use blending. By default, the engine
analyses the alpha channel contents, to determine whether it indicates
alpha blending (smooth alpha channel), alpha testing (all alpha
values are either "0" or "1"), or maybe it's opaque (all alpha values equal "1").
can always explicitly specify the texture alpha channel treatment using the
alphaChannel field in X3D.
Rendering blending is a little costly, in a general case. The transparent shapes have to be sorted every frame. Hints to make it faster:
If possible, do not use many transparent shapes. This will keep the cost of sorting minimal.
If possible, turn off the sorting, using
Scene.Attributes.BlendingSort := bsNone. See TBlendingSort for the explanation of possible
BlendingSort values. Sorting is only necessary if you may see multiple partially-transparent shapes on the same screen pixel, otherwise sorting is a waste of time.
Sorting is also not necessary if you use some blending modes that make the order of rendering partially-transparent shapes irrelevant. For example, blending mode with
srcFactor = "src_alpha" and
destFactor = "one". You can use a
blendMode field in X3D to set a specific blending mode. Of course, it will look differently, but maybe acceptably?
So, consider changing the blending mode and then turning off sorting.
Finally, consider do you really need transparency by blending. Maybe you can work with a transparency by alpha testing? Alpha testing means that every pixel is either opaque, or completely transparent, depending on the alpha value. It's much more efficient to use, as alpha tested shapes can be rendered along with the normal, completely opaque shapes, and only the GPU cares about the actual "testing". There's no need for sorting. Also, alpha testing cooperates nicely with shadow maps.
Whether the alpha testing looks good depends on your use-case, on your textures.
To use alpha-testing, you can:
alphaChannel "TEST"in X3D
Castle Game Engine can use Libpng (faster, but requires external library) or FpImage (always possible, on all platforms) to load PNG.
FPImage does not require any external libraries, and thus it instantly works (and in the same way) on all platforms. However, external Libpng is often much (even 4x) faster. That is because Libpng allows to make various transformations during file reading (instead of processing the pixels later), and it doesn't force us to read using 16-bit-per-channel API (like FpImage does).
We will automatically use Libpng if detected (and fallback on FPImage otherwise).
castle-engine compile ...or
castle-engine package ....
In Castle Game Engine 6.4 and older: To use external libpng library, define
-dCASTLE_PNG_DYNAMIC when compiling the engine. E.g. define it inside CastleEngineManifest.xml as <custom_options> and use our build tool to compile your game.
Turn on TCastleUserInterface.Culling to optimize the case when a resource-intensive control is often off-screen (and thus doesn't need to be rendered or process other events). This also matters if the control is outside of the parent scrollable view (TCastleScrollView) or other parent with ClipChildren. This is very useful when creating a large number of children inside TCastleScrollView.
When rendering 2D stuff yourself usign TDrawableImage, you can often make a dramatic speedup by using the overload that draws multiple images (maybe different, maybe the same image parts) by a single
procedure TDrawableImage.Draw(ScreenRects, ImageRects: PFloatRectangleArray; const Count: Integer); call.
We have TCastleProfiler to easily profile the speed of operations. The engine automatically uses it to log loading time of various assets. You can track the time spend in other operations (specific to your game) there too.
We have TCastleFrameProfiler to profile the time spend in a particular frame (from one
OnUpdate start to another). Use this to track short tasks that occur within a frame. The engine automatically tracks there some operations (just enable
FrameProfiler.Enabled := true and look in the log for results), you can also track other operations (specific to your game). An example output looks like this:
-------------------- FrameProfiler begin Frame time: 0.02 secs (we should have 51.22 FPS based on this): - BeforeRender: 0% - Render: 88% (0.02 secs, we should have 58.34 "only render FPS" based on this) - TCastleTransform.Render transformation: 0% - TCastleScene.Render: 47% - ShapesFilterBlending: 1% - Update: 12% - TCastleSceneCore.Update: 3% - Other: -------------------- FrameProfiler end
This example output shows that:
The majority of the work (88%) is spent doing rendering.
One conclusion is that optimizing animations (in TCastleSceneCore.Update) will not gain you much, as they only take 3% of time.
If you would like to optimize, in this particular example you should think
can I optimize rendering (TCastleScene.Render),
what else eats time in Render (there's a large difference between Render and TCastleScene.Render, so what is consuming the 41%?).
You can compile your
application with the build tool
--mode=valgrind to get an executable ready to be tested
with the magnificent Valgrind tool.
Read instructions how to use Valgrind with Castle Game Engine applications.
On Nintendo Switch, another profiler is available. More information is available in the Nintendo Switch-specific documentation of CGE (only for registered developers on Nintendo).
In general, you can use any FPC tool to profile your code, for memory and speed. See also FPC wiki about profiling.
We do not have any engine-specific tool to measure memory usage or
detect memory problems, as there are plenty of them available with
FPC+Lazarus already. To simply see the memory usage, just use process
monitor that comes with your OS. See also Lazarus units
You can use full-blown memory profilers like valgrind's massif with FPC code (see section "Profiling" above on this page about valgrind).
Copyright Michalis Kamburelis and other Castle Game Engine developers.
Thank you to Paweł Wojciechowicz from Cat-astrophe Games for various graphics.
This documentation is also open-source and you can even redistribute it on open-source terms.