Does anyone know why I'm getting these weird artifacts when I overlap 3d planes with textures on top of each other even if they are on different layers?
The smaller shapes are supposed to be hiding behind the big shape but what is happening is that the alpha channel cuts through the top shape.
I would like to add that this only happens on ios not on android.
The way I'm organising the layers is by stacking 3d planes on top of each other.
thanks in advance
So I figured it out. The solution was to disable the "Use Depth Test" and "Write to Depth.." for all overlapping materials. After changing this everything worked as expected.
Related
i wonder how the following effect could be made in Swift (SpriteKit).
I think about adding some ShapeNodes and fill them with the background image with -yscale 1.
But i think this effect was made somehow different, because the background image isn't just mirrored horizontally - it also has some graphics effects on it (it is mirrored in the shape the water pearl has and so on).
Was it done with a ShaderNode?
Does someone has an idea how i could create a same effect in SpriteKit - like water pearls which looks like they are on the "camera" and they mirror the background "waterpearl like"?
Thank you.
Hmm well you could create a bunch of water images and have them displayed randomly on the screen at some z position, however I think this effect was made in another program like unity or something of the sort, Your best bet is to create transparent water droplets as images and have them displayed randomly on your screen.
I'm trying to add a directional light in Scenekit to cast shadows, but it is causing weird artefacts on objects.
The orange block below has a material with default settings and the diffuse set to orange.
The directional light is pointing downwards, and the scale is increased, otherwise it has default settings. (Making the scale smaller still has the same issue).
When I pan the camera around the texture is covered in flickering lines and dots, it looks terrible.
This isn't visible on the simulator, only the device. What is going on and how can I fix it?
Thanks to Toyos I now know that self-shadowing is what's causing the lines. The docs for shadowBias say setting this value should correct it, but for me it made no difference.
In the end I fixed it by rotating the directional light by 2 degrees. It was originally at -90, pointing straight down. Changing this to -88 has completely removed all the artefacts.
Configure the zNear/zFar range of your light to make it as small as possible (but not clipping your world). The smaller the zRange is the more precision you will get.
You can also play with the shadowBias to limit the self shadowing artefacts
I have been working with OpenGL in iOS, and setting the colors with glColor4f(r,g,b,a) and then drawing my own color on a white UIImageView. I basically have a brush, which is then moved around my user's touch, and then it paints the color onto the canvas. But this color needs to be water paint (like smudged color)
Does anyone understand/knows how to get a water color like this app does, and how the background UIImageView has a texture on it?
https://itunes.apple.com/us/app/hello-watercolor/id539414526?mt=8
or checkout water paint in this. http://www.fiftythree.com/paper
I created a bounty on this as I am really having a hard time to grasp how to derive such smooth flowing colors out of the normal colors. Even if you guys point me in the right direction, or to some sample code on how I can get the effect of water-paint, it would be really helpful ^_^
And as a bonus, it would be also be helpful if you can point out to me how to get canvas on which it is painted on looks realistic, and blended with the paint? Does Blending/GLSL have to do with any of this?
Is there any sample project on this?
If you are still struggling with the basics of getting realistic looking water colors working, you may want to experiment/prototype in photoshop first.
http://www.zoepiel.com/tutorials/watercolor/ shows some very effective tricks for creating watercolor images with simple tools.
The most interesting one is to multiply a group of watercolor layers with a greyscale watercolor paper image. The texture of the paper makes some parts remain white, and other parts saturate with color, just like real watercolor.
Each layer remains 'wet' in the sense that the colors within it blend, but the layers are 'dry' with respect to each other.
She also explains some of her brush and blur settings and shows what they do.
Once you can produce the desired effect in photoshop, you'll have clear specifications of what you want to do and you'll be quite a bit closer to programming it out.
Looking at the examples you posted, it looks like they are using a simple Gaussian Blur with a radius of double your brush size. This may be an incomplete solution, but it's at least the first level.
We are working on a Three.js based WebGL project, and have trouble understanding how transparency is handled in WebGL. The image shows a doublesided surface drawn with alpha = 0.7, which behaves correctly on its right side. However closer to the middle strange artifacts appear, and on the left side the transparency does not seem to work at all.
http://emilaxelsson.se/sandbox/vis1/alpha.png
The problem can also be seen here:
http://emilaxelsson.se/sandbox/vis1/
Has anyone seen anything similar before? What could the reason be?
Your problem is that transparent objects needs to be sorted and rendered in a back-to-front order (if you try to change the opacity of your mesh from 0.7 (transparent) to 1.0 (opaque), you can see that the z-buffer works just fine).
See:
http://www.opengl.org/wiki/Transparency_Sorting
http://www.opengl.org/archives/resources/faq/technical/transparency.htm (15.050)
In your case it might be less trivial to solve, since I assume that you only have one mesh.
Edit: Just to summarize the discussion below. It is possible to achieve correct rendering of such a double-sided transparent mesh. To do this, you need to create 6 versions of the mesh, corresponding to 6 sides of a cube. Each version needs to be sorted in a back-to-front order based on the 'side of the cube' (front, back, left, right, top, bottom).
When rendering choose the correct mesh (based on the camera viewing direction) and render that single mesh.
The easy solution for your case (based on the picture you attached), without going to expensive sorting and multiple meshes, is to disable depth test and enable face culling. That produces acceptable results if you do not have any opaque objects in front of the mesh.
To best illustrate the issue I'm having, I created a short screen grab. Watch it here: http://cl.ly/1o3p3x2e2J1a1d3d2N1Q
Basically, the stars on the screen, as they're animated across the screen from right to left, are dimming and brightening on their own. I'm not intending on this happening. When you zoom in, the issue disappears.
My hunch is that this has to do with the size of the objects being drawn and the pixel boundaries. Is this correct? What is the best way to go about fixing this issue?
Thanks!
---Edit---
Here's how I'm loading the texture: http://pastebin.com/RDc8x7Te
And, here's how I'm setting up OpenGL ES: http://pastebin.com/SpvAqPqA
You use nearest and linear for scaling textures, which are both not very accurate. You might want to use linear for both, or build mipmaps. Also in case you use an orthogonal view, try aligning your geometry on pixels.