I have simple ARKit app (using SceneKit) with cubes floating in space that I am shooting with other objects. I created .scnp file with Fire as a template and customized it to sort of look like explosion.
Everything looks good and works on collision, but my whole particle effect takes whole screen. I tried every property available on the .scnp file but the size is still enormous.
How can I set the effect area size? For example to be slighty bigger than my cubes (with width 0.1 meters).
This is how run the explosion:
let fire = SCNParticleSystem(named: "explosion.scnp", inDirectory: nil)
contactNode.addParticleSystem(fire!)
contactNode is my target cube.
The particle system property you’re looking for is particleSize. (There’s a control for setting that property in the Xcode particle system GUI editor, but I forget what it’s labeled...)
The docs for that property say:
The rendered size, in units of the scene’s world coordinate space, of the particle image.
In ARKit, scene units are the same as real-world meters. So while a particle size of, say, 10x10 might make sense in some arbitrary scene, in AR that makes each particle the size of a house. You probably want values somewhere in the scale of millimeters to centimeters (0.001 - 0.01).
Related
I am making a defense game. Since the concept of the game is Christmas, we are using Christmas-specific particles, but since the number of sprites used for particles is so small, we need a way to increase the number of sprites. Is there a way to increase it in a particle system?
I've tried many things in the 'particle system' in the particle inspector to increase the number of particles, but I can only adjust the size.
Double-check that your Max Particles count is set to the desired number (default: 1000). If it is, then the settings you're looking for are located in the Emission and Shape modules of the Particle System:
By default, the Rate over Time is 10 particles per second; you could increase this value to have more particles. Alternatively, you could create Bursts of particles instead.
The default Shape is a 25-degree-angle Cone which faces the Z-axis. Feel free to change the Shape and/or the properties like position and scale to get your desired result.
I would also suggest looking at Unity Learn: Introduction To Particle Systems if you're new to this system.
I'm trying to figure out why my Object's textures keep turning white once I scale the object down to 1% (or less) of its normal size.
I can manipulate the objects realtime with my fingers and there is a threshold where all the textures (except a few) turn completely ghost white, as shown below:
https://imgur.com/wMykeFw
Any input to fix is appreciated!
One potential cause of this issue is due to how certain shaders can miscalculate how to render textures when scales are set to low values.
To be able to render this asset so small using the same shader, re-import the mesh with a smaller scale factor (in the mesh import settings), and that may fix it.
select ARCamera then camera, in the inspector, select the cameras clipping plane and increase it(you want to find the minimum possible clipping that works to save on memory, so start at 20000, and work your way backwards til it stops working, then back up a notch).
next (still in the cameras inspector), select Rendering Path and set it to Legacy Vertex Lit
this should clear it up for you
I saw some documents saying that there is no concepts of length in Unity. All you can do to determine the dimensions of the gameobjects is to use Scale.
Then how could I set the overall relative dimensions between the gameobjects?
For example, the dimension of a 1:1:1 plane is obviously different from a 1:1:1 sphere! Then how could I know what's the relative ratios between the plane and the sphere? 1 unit length of the plane is equal to how much unit of the diameter of the sphere!? Otherwise how could I know if I had set everything in the right proportion?
Well, what you say is right, but consider that objects could have a collider. And, in case of a sphere, you could obtain the radius with SphereCollider.radius.
Also, consider Bounds.extents, that's relative to the objects's bounding box.
Again, considering the Sphere, you can obtain the diameter with:
Mesh mesh = GetComponent<MeshFilter>().mesh;
Bounds bounds = mesh.bounds;
float diameter = bounds.extents.x * 2;
All GameObjects in unity have a Transform component, which determines its position, rotation and scale. Most 3D Objects also have a MeshFilter component, which contains reference to the Mesh object.
The Mesh contains the actual shape of the object, for example six faces of a cube or, faces of a sphere. Unity provides a handful of built in objects (cube, sphere, cyliner, plane, quad), but this is just a 'starter kit'. Most of those built in objects are 1 unit in size, but this is purely because the vertexes have been placed in those positions (so you need to scale by 2 to get 2units size).
But there is no limit on positinos within a mesh, you can have a tiny tiny object od a whole terrain object, and have them massively different in size despite keeping their scale at 1.
You should try to learn some 3D modelling application to create arbitrary objects.
Alternatively try and install a plugin called ProBuilder which used to be quite expensive and is nowe free (since acquired by Unity) which enabels in-editor modelling.
Scales are best kept at one, but its good to have an option to scale - this way you can re-use the spehre mesh, or the cube mesh, (less waste of memory) by having them at different scales.
In most unity applications you set the scale to some arbitrary number.
So typically 1 m = 1 unit.
All things that are 1 unit tall are 1 m tall.
If you import a mesh from a modelling program that is the wrong size, scale it to exactly one meter (use a standard 1,1,1 cube as reference). Then, stick it inside an empty game object to “convert” it into your game’s proper scale. So now if you scale the empty object’s y axis to 2, the object is now 2 meters tall.
A better solution is to keep all objects’ highest parent in the hierarchy at 1,1,1 scale. Using the 1,1,1 reference cube, scale your object to a size that looks proper. So for example if I had a model of a person I’d want it to be scaled to be roughly twice as tall as the cube. Then, drag it into an empty object of 1,1,1 scale this way, everything in your scene’s “normal” size is 1,1,1. If you want to double the size of something you’d then make it 2,2,2. In practice this is much more useful than the first option.
Now, if you change its position by 1 unit it is moving effectively by what would look like the proper 1 m also.
This process also lets you change where the “bottom” of an object is. You can change the position of the object inside the empty, making an “offset”. This is Useful for making models stand right on the ground with position y=0.
When I move towards my .dae imported model, it disappears. I'm not "inside" the mesh yet, visibly at least, so I don't know what the deal is.
It looks like your object is closer than the scene-view camera's "Near Clip Plane", and is not being rendered as a result. The default editor "near clip plane" distance is around 0.3 units, so it shouldn't normally interfere with your objects.
Check that your object scale is correct. If your object is very small, the scene camera's near clip plane will seem much farther in comparison, and will appear to clip objects more aggressively.
You can create a default "Cube" primitive to check the size of your objects. Cubes are 1 unit in all dimensions by default, and most of the time it's a good idea to roughly map one unit to a real-world scale of 1 meter. If your object is considerably smaller than the cube, you may want to try scaling them up and seeing if that helps.
F key is a shortcut key that will automatically zoom and focus to an object. Select the GameObject and press F. This problem should be gone.
If the problem is still there, select the Camera and change the Clipping Planes Near to 0.3 and Far to 50000. You can mess with these values until Object stops disappearing. Although, pressing F should solve it.
I am developing an application for iPhone.
I am using OpenGL to display a 3D object in the screen, with the camera view as background.
I'd like to know how can i change the OpenGL ES unit to centimeters/meters.
How can i do that?
You dont.
Thought experiment time!
First imagine you have sphere 1 centimeter in diameter. And you have a camera 10 centimeters away. You would see a small sphere in the center of the frame.
Now imagine you have a sphere 1 kilometer in diameter and a camera 10 kilometers away. How would you expect the image to be different?
The correct answer is you would not expect the image to change at all. All that really matters is the relative sizes of things. So the unit type you attribute to the the numbers only matters to the programmer, and not to the program.
So you simply mentally declare that one unit is equal to one centimeter and create your objects and world according to that scale. There is no code level change to make this happen. It's merely a convention that you use to help you build things in correct dimensions relative to each other.
OpenGL does not have a notion for units. It just uses unit-less values. What these values mean is up to you. They just have to be consistent. So if your objects coordinates and viewing parameters are all specified with meters in mind and you have an object whose coordinates are in centimeters, just scale that object by a factor of 0.1.