i am trying to cast an shadow on an totally transparent plane in SceneKit on OSX. I am struggling with this problem since several hours and do not come to any solution.
My Purpose is to generate an Screenshot of several objects with an transparent background and just the shadow on an invisible Plane.
Do you have any suggestions for me how i can make this with apples SceneKit?
Do i have to program my own shader, can i make this work with shadermodifiers or can i use built in functionallity?
UPDATE:
I find an alternative solution for anyone who needs:
create a white plane under 3D model, note that the color of plane must be pure white.
set blend mode of plane's material to SCNBlendModeMultiply.
set light model of plane's material to SCNLightingModelLambert.
This works because any color multiply white color (1, ,1, 1) return itself And lambert light model will not take account of directional light, So the plane will always be background color which look like transparent. Another benefit of this solution is you don't need change light‘s shadow rendering mode.
For people who used to inspector of Xcode.
According to SceneKit: What's New.
First, add a plane under you model. Then prevent it from writing to colorBuffer.
Second, change your light model's shadow rendering mode to deferred. Notice that you must use light which can cast shadows.
Oily Guo, your solution works. Here the solution is in code:
Configuration of the light source:
light.shadowColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.4)
light.shadowMode = .deferred
And for the floor (ie. SCNFloor underneath your objects):
material.diffuse.contents = UIColor.white
material.colorBufferWriteMask = SCNColorMask(rawValue: 0)
I do not have an answer to your question, however I have a workaround:
Render your scene and keep the image in memory
Change all the materials in your object for pure black, no specular
Change the plane and the sky to a fully white material, lights to white
Render the scene to another image
On the second image, apply the CIColorInvertand CIMaskToAlpha Core Image filters
Using Core Image apply the Alpha Mask to the first render.
You'll get an image with a correct Alpha channel, and transparent shadows. You will need to tweak the materials and lights to get the results you want.
The shadow may become lighter on the edges, and the only way around that is rendering it as yet another image, and filling it with black after the Mask to Alpha step.
Related
I am new to three.js and I created a classic sphere, wrapped with a world color map & bump map and an alpha map for clouds, and directional sunlight. How can I now add an earth at night texture only on the shadow side of the globe? The globe is rotating, so I couldn't just create 2 half-spheres.
I tried adding this grayscale mask to the texture, but it is also visible in daytime. I then tried illuminating the map with a different light aimed at the dark side, but couldn't selectively target only one material. I didn't quite understand if I need to use "emissiveMap".
Could I shine a light through a semi-transparent map/mask from the center of the earth to make the cities visible, or is there some type of "black light" to only make selected color/map areas shine in the dark?
I don't need any glowing effects, I just want it to be visible. Will I have to create individual light points or learn to use fragment shaders?
I'm trying to make a very simple shadow shader which consists of a plane with a shader showing a radial gradient on colors and alpha.
Beneath this shadow lies another plane with the same kind of shader but linear.
And as a background of all this, a linear gradient from dark blue to light blue.
The problem is that when my camera approaches the ground, the plane of the shadow masks the floor.
Why does it happen and what can I do to prevent that?
https://codesandbox.io/s/epic-sun-po9j3
https://po9j3.csb.app/
You'd need to post code to check for sure but it likely happens because three.js sorts the order it draws things based on the center of the objects and their distance from the camera.
You can force a different order by setting Object3D.renderOrder
three.js also generally draws opaque things before transparent things so my guess is your ground plane and your shadow plane are both set to transparent: true but the ground can be set to transparent: false in which case it will be drawn first.
You might find this article useful. It shows a similar example.
As for why there is a hole it's because of the depth buffer. If something in front gets drawn first then the pixels behind are not drawn. So if the shadow happens to be drawn first it ends up looking like a hole because the pixels of plane behind it are not drawn.
See this
I am rendering a sofa using r71 but the texture quality is not proper. If I render it through r58 then it looks really good. It is a bug or what?? Below are the images, first one is rendered via r58 and second one via r71.
Coming from r58 a lot of things has changed, for you especially how they calculate gamma and hardwireing the ambient term to the diffuse color.
The main difference I see is your model appears darker.
To make the model appear brighter you could set the materials color to white: material.color.setHex( 0xFFFFFF );.
If this is still not bright enough I discovered a little Hack by setting the HSL Lighting value to something > 1. material.color.setHSL( 0, 0, 6 );
Without providing the code on how you create your material its only a shot in the dark.
the color of a black image , or the black part of a image, can not be changed.
I set the image's color to red, but the image is still black.
Is that a desired feature?
What i want is , the image is changed to red.
the Unity version is 5.0.1f.
I am using the new UI.
To understand the source of the problem, you have to understand how "changing colors" work. It's nothing but a simple multiplication. In RGB terms, "black" is a vector of (0, 0, 0) — and it's pretty obvious, that whatever you multiply the 0 by, it stays black.
If you want the template image to be able to change to any color, use white.
To modify colours in a more complex way, you have to understand how the Color property of a Image component works. UI system hides a lot of complexity underneath (and it's good). Basically, Color modifies the vertex colours of a mesh. Since you don't usually specify a material, a default sprite material is used, and it uses a default sprite shader. And inside this shader, when it paints the pixels on the screen, it multiplies the vertex colours by the texture colour sampled at this pixel, and that's how it produces the end result. If you want the colours to be combined in a different way, you'll have to write a custom shader — which is really not as hard, but you probably don't need it for what you're trying to do in the scope of this question.
Black stays black.
White, however, will change with whatever Color you choose, so if you use an image editor and make your image be white instead of black, the image can then be whatever color you choose within Unity.
Check to see if your image has an alpha channel. You can do this with GIMP or Photoshop. If it does, then check your shader/material to ensure that it's set to transparent/diffuse (and not just diffuse). Diffuse only doesn't apply the alpha property to the material.
Also, it doesn't look like you assigned a material...
Make sure you have used yourImage.canvasRenderer.SetColor.
For example:
damageAnim.canvasRenderer.SetColor (new Color (255, 255, 255, 255));
Is it possible in three.js to create transparent/invisible plane, which can receive shadows? My aim is to draw some object on 3d canvas without background (so I can see webpage behind the canvas element). I want the object to cast shadows on the background and I thought, if I could make an invisble plane, then webpage background is still visible. Shadows are casted on the plane and it seems like shadows are on the webpage.
Right now I can make a white plane with opacity 0.5 (or similar), but this way the plane is visible. Ideally the plane should be completely invisble (except for shadows).
EDIT: I created an exampled (based on this): http://jsfiddle.net/s5YGu/2/
Here I have opacity 0.5, but you can see the plane. If I set opacity to 0, then the whole plane and the shadows disappear.
I made this work by hacking on basic shader, here is working shader code http://pastie.org/5088640
It has no drawbacks AFAIK, like opacity: 0.1
Yes, you can achieve the effect you want, and it looks pretty good on my machine at least. :-)
Here is a fiddle: http://jsfiddle.net/ZXdV3/25/
There are a couple of issues. First, you will have to set alpha: true in the renderer constructor args.
Second, although I assume you'd like the plane to be completely transparent, you'll have to settle for material.opacity = 0.1, or so.
Third, if you are placing a canvas over the webpage, and you want the web page to be interactive, you are going to have to suppress pointer events in the canvas (I'm not sure if IE supports this, though): container.style.pointerEvents = 'none';
three.js r.67