Camera minZ and maxZ

[Jose Vicente]

Hello.

 

I'm trying to understand how camera minZ and maxZ works, to define it correctly for my scene. If I'm, not wrong, those values define the position for near and far planes.

I'm not able to define them properly.  In  http://www.babylonjs-playground.com/#1JNDSK#3, I have defined a sphere placed at 0, 0, 0, with diameter = 2, and there is a camera located a 0, 0, 20.

Camera minZ is set to 38, and the sphere starts dissapearing. Lower values, like 37, doesn't affect the sphere.

I don't understand this behavior.  Sphere min Z value its Z = -1, and I can't undestand why minZ = 37 doesn't hides the sphere and value = minZ =38 hides partially.

Anyone can help?

Thanks in advance.

Best Regards.

 

[GameMonetize]

Hello

minZ and maxZ define the clip planes and are used to create the projectionmatrix: https://github.com/BabylonJS/Babylon.js/blob/master/src/Cameras/babylon.camera.ts#L410

A projection matrix is build like this: https://github.com/BabylonJS/Babylon.js/blob/master/src/Math/babylon.math.ts#L2706

minZ and MaxZ are used to scale the depth values from [minZ,maxZ] to [0,1]

Here is an example to better capture it:

http://www.babylonjs-playground.com/#1JNDSK#8

 

If you want to get a clipPlane (not a nearPlane), you can use  scene.clipPlane;

 

 

[Wingnut]

I built a fancy tester.  http://www.babylonjs-playground.com/#1JNDSK#10

Ain't I just something?    Looking straight -z, on-screen position-reporting, fancy edges-rendering, severely-reduced mousewheel sensibility, severely-adjusted camera.speed which is barely working if at all.  Fancy stuff.  All designer label stuff.  heh

Don't be messing around in MY version... unless you are dressed for dinner.  High class PG.  Wash-up a bit and dress appropriately, eh? 

[dbawel]

@Wingnut - Wow, am I sensing an ego here? You crack me up dude! Always good for a little comic relief.

[Jose Vicente]

Thanks to all. Finaly I have ben able to understand how they work.

Regards.

[Venerated1]

Save doesn't seem to be working for some reason, but you can copy and paste this into playground.

This is a fun demo of a my random stars rather than a skybox.  They require a pretty crazy maxZ. This was also my playing around with creating instances.  With some random scaling and the for loop set to 10,000 it's even more beautiful

var createScene = function () {

    // This creates a basic Babylon Scene object (non-mesh)
    var scene = new BABYLON.Scene(engine);
    scene.clearColor = true;

    // This creates and positions a free camera (non-mesh)
    var camera = new BABYLON.FreeCamera("camera1", new BABYLON.Vector3(0, 5, -10), scene);
    camera.setTarget(BABYLON.Vector3.Zero());
    camera.maxZ = 32000;

    // This attaches the camera to the canvas
    camera.attachControl(canvas, true);

    // This creates a light, aiming 0,1,0 - to the sky (non-mesh)
    var light = new BABYLON.HemisphericLight("light1", new BABYLON.Vector3(0, 1, 0), scene);

    // Our built-in 'ground' shape. Params: name, width, depth, subdivs, scene
    var ground = BABYLON.Mesh.CreateGround("ground1", 6, 6, 2, scene);

    var matForStars = new BABYLON.StandardMaterial("starMat", scene);
			matForStars.emissiveColor = new BABYLON.Color3(1, 1, 1);
			matForStars.specularColor = new BABYLON.Color3(0, 0, 0);
			matForStars.diffuseColor = new BABYLON.Color3(0, 0, 0);

			var star = BABYLON.Mesh.CreateSphere("star", 1, 20, scene);
			star.material = matForStars;
			star.position.z = 14000;
			
			// Create some instances, make a bunch of stars
			var stars = new Array();
			for (var i = 0; i < 1000; i++) {
				var random1 = (Math.random() - 0.5) * 32000;		
				var random2 = (Math.random() - 0.5) * 32000;
				var random3 = (Math.random() - 0.5) * 32000;
			
				var magnitudeStar = Math.sqrt(random1 * random1 + random2 * random2 + random3 * random3);
			
				if (magnitudeStar < 14000 || magnitudeStar > 16000 ) {
					i--;
				}
				else {
					stars[i] = star.createInstance('Instance' + i);
					stars[i].position.x = random1;
					stars[i].position.y = random2;
					stars[i].position.z = random3;
				}
			}

    return scene;

};