I have a spot light over a SCNNode (skull), I want shadows to cast only in the skull.
How could I prevent the other nodes (see node underneath the skull in the photo) that aren't the skull from receiving any kind of shadow?
Related
I am learning ARKit. I'm placing Virtual Objects in Augmented Reality scene and struggling in these problems!
I am using this demo project from github
1- How to add only one directional light for all (separate) nodes in SceneView of SceneKit & Move directional light with camera position? So that my added shadow can also move with light direction.
If I translate the object shadows are working as it should be. But If I rotate object now shadow should not move on the plan. They are moving because of light is at fixed position.
2- Shadow is looking fine only in case If I add only one object on the plane. But If I add two or more objects more directional lights are adding in SceneView. Now every object has more than one shadows. I want it to restrict only one shadow.
I have added light and shadow plane in sceneKit editor. (not programmatically). Here are my scenekit editor's screenshots.
3- I have read and confirmed that shadow are adding only If I set directional light property to deffered. But in this case app is crashing If I call remove all nodes from sceneView's root node. My removing nodes code is.
self.sceneView.scene.rootNode.enumerateChildNodes { (node, stop) -> Void in
node.removeFromParentNode()
print("removed ", node.name as Any)
}
You can watch my apps video for more clearance. Apps video, How it is working now
My requirement is to add only one shadow for every object. When I Rotate and translate objects shadows should look real.
I also have tried it as removing light from scn file of vase, and add a separate light.scn file having only light in it. added These two (vase and light) nodes in sceneView. But No shadow is appearing.
Directional lights are interpreted from the shader only with their direction (that one light-red vector coming out of the node in Xcode). It does not matter where the position of the light is. Directional light are often used for imitating sun light.
I implemented a similar project so here is my attempt.
I added one directional light from a separate SCN-File to the scene when I initialize the SCNScene.
My settings for it:
castsShadow: true
mode: deferred (my App is not crashing, if I remove my objects from the scene :/ )
And actually thats it to make it work in my project.
One thing about your planes: I think you have not disabled castsShadow on the planes. Therefore a user can see the planes.
Edit:
I could reproduce the crash. It does occur when removing the directional light. Thats why the app is not crashing in my project. So you could do it like me and add the directional light in viewDidLoad() for example.
I'm working on a sprite kit game and I'm trying to create a particular silhouette lighting effect whenever objects pass in front of a particular object (in this case a red sun). I want anything in front of it to appear black, and everything else to appear as normal (so if an object is partially in front, only that part should be black).
But I'm not sure how to do it in an efficient way. I've tried playing around with different SKBlendModes but so far haven't had much success. The major challenge seems to be achieving the effect whilst preserving the colour of the sun behind.
I'm not sure if it's possible to achieve this with the existing SKBlendModes, or if something else will be required.
I've attached a diagram to illustrate what I'm going for and an image of the current best fit.
You can create the silhouette effect with an SKCropNode, a mask node, and a background node. An SKCropNode selectively mask pixels of the sprite nodes in its node tree. Here, it will provide the silhouette effect by hiding/revealing portions of a black circle.
First, create the following objects:
A shape node (yellow circle) with its zPosition set to -1
A sprite node (black circle) with the same size as the yellow one
A crop node (SKCropNode) and a mask node (SKNode)
Next,
Add the yellow circle at the center of the scene
Add the black sprite as a child of the crop node
Assign the mask node to the maskNode property of the crop node
Add the crop node at the center of the scene
Since the mask node currently has no children, the black circle will be completely hidden and the entire yellow circle beneath it will be visible. As we add sprites to the mask node, the pixels of the black circle that intersect with the sprite will be unmasked (shown in black), producing the silhouette effect.
All that's left is to add a "presentation" node that will be displayed when the mask node's sprite is outside of the black circle. The presentation node will mirror the mask node's sprite's position and rotation. This should be done in didSimulatePhysics to ensure that the presentation and mask-node sprites are synchronized after the physics and actions have been updated.
But wait...if the presentation node moves over the yellow circle, won't it eclipse the Sun? Not if we set its presentation node's zPosition to -2.
The following shows an implementation of the above:
This problem was interesting to me, so I came up with a simple solution. It's not perfect nor does it scale very well, but the basics fulfill your need I believe and it may point others in the right direction.
I don't use any special SKBlendMode. Instead, I am using a duplicate object for the object which moves in front of the sun. This duplicate object is cropped using an SKCropNode with a duplicate of the sun as the maskNode. So, my node tree is as follows:
SKSpriteNode (sun) (the white sun)
SKSpriteNode (object1) (the rotating purple square with alpha 0.25)
SKCropNode
maskNode: SKSpriteNode (sunDuplicate = [sun copy])
SKSpriteNode (object1duplicate, same size as object1 but with [SKColor blackColor])
Inside the update method, align the duplicate with the original to ensure animation is properly forwarded.
- (void)update:(CFTimeInterval)currentTime {
self.object1duplicate.position = self.object1.position;
self.object1duplicate.zRotation = self.object1.zRotation;
}
As I said, this doesn't scale very well since you'll manually have to add duplicate objects and keep track of them for each object moving in front of the sun object. Perhaps SKShader can be of more elegant use.
I have 2 SKSpriteNode objects, and I want to crossfade them.
One of the easiest way is to create a fadeOut SKAction and a fadeIn SKAction, and apply them to the SKSpriteNode objects. But the problem of this approach is that during the action both of them have the alpha under 1.0, which looks not so good.
For example, I'd like to dissolve the red square SKNode to a green round SKNode
If just fade out the red square and fade in the green round during the action it'll look like this
So you can see background through these 2 objects. I hope to dissolve these 2 objects like this:
In UIKit I can use UIView.transitionWithView but in SpriteKit I only found a similar method for presenting scenes (SKViewObject.presentScene: transition:). So is there anyway to make a dissolve transition for SKNodes?
There's little you can about the background coming through when adjusting the alpha settings on both nodes. A possible hack could be to temporarily insert a solid node in front of your background but behind both other nodes until the action is done. At which point you remove it.
The node should be in the shape of both nodes cross-section (pardon the sloppy artwork on my part):
I searched a lot for this question and I nearly decided to use a shader to do this kind of dissolve (since you can directly edit the pixel in a shader), but then I found that there's an unusual way to solve this problem. It may not be useful for every situation, but if your background doesn't do things like scroll or zoom, this approach may be the easiest. In simple words, just create a screenshot for the current screen and display it at the top, then change your node to the sprite you need, and at last fade out the screenshot you took.
So at first you have to make sure all the nodes are in the correct node tree. Then use SKViewObject.textureFromNode(rootNode) to create the screenshot, make a sprite node from this texture, and add it to your screen. Then, you can create the fade out SKAction to fade out this screenshot sprite. You may also remove it when the action ends.
Using this approach, during the fade out the screen will just look like this:
I added a background SKSpriteNode as a child to my SKScene. This node itself has some children nodes. Each child has some colored pixels as well as totally transparent pixels. The children nodes are moving across the screen and sometimes intersect each other.
I'd like to make the intersecting colored areas of the children fully transparent as they move so that the background sprite shows through. For the non-intersecting areas of each child, the node should appear as normal. I tried playing around with the blendmode but couldn't get the desired effect. Any ideas how to do this? Or, is there a way to do this outside of SpriteKit?
Thanks
I don't think there are commands to achieve what you want. You can change the the entire texture/image of a sprite, you can change part of a sprite's texture/image appearance by using a filter but you cannot specifically modify part of a sprite's texture/image. To be more specific, a sprite's alpha property applies to the entire sprite and not just part of it.
I have a large sprite. I want to animate parts of it. Obviously I don't want 30 images of said sprite, I want only the difference, that light blinking or something.
How do I handle that? So far using many images for sprite animations has been way to go for me.
A SKSpriteNode can have children, so you can overlay as many as you like on top of a given SKSpriteNode.
For example if you had a christmas tree, you could put 20 lights on the tree by just adding a child SKSpriteNode for each light and positioning it appropriately. You could then have each of those lights animate independently and dynamically.
You can create you sprite with something like layering.
In practice it will be looking like sprites (that will be animated separated) under 'big' sprite that you do not want to animate.