Camera view matrix computed for each frame

[JulienGobin]

Hi everyone,

 

First of all, happy new year and thanks for this amazing webgl engine.

 

I noticed the view matrix of the camera is computed for each frame when BABYLON.Camera.prototype.getViewMatrix is called by BABYLON.Scene.prototype._renderForCamera (called by BABYLON.Scene.prototype.render).

 

BABYLON.Camera.prototype.getViewMatrix is in two parts:

this._computedViewMatrix = this._getViewMatrix();// BABYLON.Camera.prototype._getViewMatrix is overrided in sub-classes (ArcRotateCamera and FreeCamera compute for each frame a matrix and return it)

and

if (this.parent && this.parent.getWorldMatrix) {            if (!this._worldMatrix) {                this._worldMatrix = BABYLON.Matrix.Identity();            }            this._computedViewMatrix.invertToRef(this._worldMatrix);            this._worldMatrix.multiplyToRef(this.parent.getWorldMatrix(), this._computedViewMatrix);            this._computedViewMatrix.invert();            return this._computedViewMatrix;        }

which computes the view matrix if the camera has a parent.

 

Is it on purpose that the view matrix is computed for each frame? Is it better for the memory? (instead of caching values like it's done for the meshes; BABYLON.Mesh.prototype.computeWorldMatrix)

[GameMonetize]

This is a update I get on my to do list actually

[JulienGobin]

Ok, thank for your fast reply .

I'm already working on a system that makes the job. (Because i really need it), maybe i can send you a pull request when i have finished (tomorrow) ?

 

(I'm also working on a system, based on this first one, that forces the wireframe display when the fps is shutting down when a camera is moving; of course it's optional and parametrable. Will you be interested by it ?).

 

 

Here what i have done so far :

 

http://jsfiddle.net/JulienGobin/7DT4R/

http://jsfiddle.net/JulienGobin/4QhX4/

[JulienGobin]

Here it is https://github.com/BabylonJS/Babylon.js/pull/122

[GameMonetize]

Excellent and thank you for your contribution:)

 

I have a question about wireframe mode: does it really speed things up?

[gwenael]

That could be nice. I guess it speeds up things when meshes have a lot of vertices but it doesn't when the scene contains only meshes will a few number of vertices (not a lot of rasterization to do I guess)

[GameMonetize]

In my case this is always worse:(

[gwenael]

Really? I didn't check how you do the wireframe rendering but my first thought would be that's it's faster to render in wireframe mode. Weird. Anyway, I guess what JulienGobin uses here http://jsfiddle.net/JulienGobin/4QhX4/ could be modified to use a fastest material when the camera is moving (instead of wireframe). That's kind of cool.

 

this._scene.activeCamera.forceWireframe would be replaced by this._scene.activeCamera.forceFastestMaterial and the material would be set for the mesh in BABYLON.Mesh.prototype.render

[GameMonetize]

I prefer this way actually. Gfx cards are not really good at drawing wireframe

[JulienGobin]

Thank for your reply, the new pull request (without the wireframe stuff) is here : https://github.com/BabylonJS/Babylon.js/pull/126

 

For the wireframe stuff i'm really surprised that this display mode is worst than the normal one. I will force myself on more test next time ^^'.

(Edit : wrong link, my bad)

Edited January 14, 2014 by JulienGobin

[GameMonetize]

You will be in the next version (1.8.5). gg! and thanks a lot for your help

[GameMonetize]

Hey Julien,

 

I think there is a bug with your cache: try the train demo and switch to camera attached to the train

[GameMonetize]

Ok I've fixed it

[gwenael]

Thanks. Could you commit the fix please?

[GameMonetize]

it is part of the upcoming update