I am trying to render cylinders for a CAD-like project. As multiple of these will be nested in each other, I am looking to display them similar to this: http://mrwadeturner.pbworks.com/f/1305815353/FC_Cylinder_41702_lg.gif
i.e. I want the outline and the base and bottom circles traced out and the rest should be (semi-)transparent.
Note that this is different from using regular wireframe settings, because that will trace out every face of the sides of the cylinder. The other approach I found - rendering the object twice, once in color and slightly enlarged and once it "regular" version on top - unfortunately won't work either, since multiple cylinders will be nested.
I think this should be possible with custom vertex and fragment shaders, but I am not very proficient in using them. What would be the best way of achieving this effect?
Thanks a lot!
Sound like you just need to apply various textures to the same faces. Next you want to try to create custom texture that is going to be a simple transparent .png image with solid dashed border. Then you'll have to set side:THREE.FrontSide and side:THREE.BackSide to your textures and play around with depthTest.
Another approach is to use lines that you age going to create vertex-by-vertex. See this example for custom line implementation: Hilbert curve and Shapes generation
Hope that helps!
Related
I've been asked to build something similar to this so that customers can draw basics shapes of kitchen tops. Similar to that in the image below but also have dimensions.
It looks like konva has support for basic shapes like rectangle and circle etc and it also includes a transformer which allows for resizing. However, I think if I want to build a custom shape like the one in green and have individual sizing i.e. resize each individual line. I am going to have to build something myself.
I was hoping someone could point me in the right direction. I have seen an example where someone has used a "line" class which takes a series of points and then sets the attribute to closed which fills in the shape. Obviously I would need to extend this to allow the custom resizing. However, Im not sure this is the correct path to head down?
Any suggestions?
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How about using rectangles and having an option to snap them together. It should be fairly simple to do the edge detection and snapping. Then show the result as a Konva.Line around the perimeter.
Then you can show all the control handles for the rectangles except those on the sides where another Rect has joined.
I need to add this classic effect which consist in highlighting a 3D model by stroking the outlines, just like this for example (without the transparent gradiant, just a solid stroke) :
I found a way to do this here which seems pretty simple and easy to implement. The guy is playing with the stencil buffer to compute the model shape, then he's drawing the model using wireframes and the thickness of the lines is doing the job.
This is my problem, the wireframes. I'm using OpenGL ES 2.0, which means I can't use glPolygonMode to change the render mode to GL_LINE.
And I'm stuck here, I can't find any simple alternative way to do it, the most relevant solution i found for the moment is to implement the wireframe rendering myself, which is clearly not the easiest solution. To draw my objects I'm using glDrawElements with GL_TRIANGLES as primitive, I tried to use GL_TRIANGLE_STRIP as primitive but the result is definetely not the right one.
Any idea/trick to bypass the lack of glPolygonMode with OpenGL ES? Thanks in advance.
Drawing Outline or border for a Model in OpenGL ES 2 is not straight forward as the example you have mentioned.
Method 1:
The easiest way is to do it in multiple passes.
Step 1 (Shape Pass): Render only the object and draw it in black using the same camera settings. And draw all other pixels with different color.
Step 2 (Render Pass): This is the usual Render pass, where you actually draw the objects in real color. This every time you a fragment, you have to test the color at the same pixel on the ShapePass image to see if any of the nearby 8 pixels are different in color. If all nearby pixels are of same color, then the fragment does not represent a border, else add some color to draw the border.
Method 2: There are other techniques that can give you similar effects in a single pass. You can draw the same object twice, first time slightly scaled up with a single color, and then with real color.
Using THREE.Shape, I can create holes, but rather than holes, I wish to define a clip mask.
I ONLY want to render the shape within a mask, similar to html's canvas/context .clip()
Is there a way to do this using holes or other method?
EDIT:
So, more background, I was using canvas to render segments, and imported them into three as planes.
The mouth was 1 canvas, and I was able to clip mask the teeth and tongue onto the black part.
See the whole movie at http://zsenji.com (rendered using the old canvas method)
Anyway, now I'm updating everything to use threejs and no more canvases rendered as planes.
I'm going to try three csg , which can hopefully intersect two geometries. https://stemkoski.github.io/Three.js/CSG.html
Then all I would have to do would be extrude the black of the mouth, and intersect it with the teeth/tongue. I will update
It worked.
I used very simple intersect, similar to https://github.com/chandlerprall/ThreeCSG/blob/master/examples.html
It's a little slow and there are still some other problems relating to overlapping paths, but for this issue, this was the fix.
All the different fills you see are three shapes
Using three.js am trying to create a floor that reflects the objects that sit upon it. Preferably the floor material should reflect not like a mirror but in a more 'matte' or diffused way.
To achieve this I looked to Jaume Sanchez Elias who has made a great example using a cube camera: Look for the "smooth material" example on this page:
http://www.clicktorelease.com/blog/making-of-cruciform
Here is my attempt using the same technique. But as you see the reflections are misplaced, they do not appear underneath the mountain objects as expected.
http://dev.udart.dk/stackoverflow_reflections/
I am looking to correct this or to use any other technique that will achieve a more correct diffused reflection.
There are three.js examples using the cube camera technique but they all create mirror-like effects not a soft reflection.
Vibber. Parallax-corrected cubemaps, the technique used in cru·ci·form, only works for closed volumes, like cubes. It works really well to simulate correct reflections inside a room, but not so much for outdoors or open/large scenes. They also can't reflect anything that it's inside the cubemap, you'd have to split the volume in many sub-volumes.
I can think of a couple of solutions for what you want to achieve:
SSR: Screen-space reflections, you can find more info in many places on the internet. It's not the most trivial of effects to implement, and you might have to change the way you render your scene.
Simpler post-processing approach: since you have a flat floor, render the mountains vertically flipped on a framebuffer object, blur it, and render the regular scene on top. For extra effect, render the depth of the flipped mountains, and use that value as the blur radius, to get diffuse reflections.
As always, there's a ton of ways to achieve the (un)expected result :)
I want to do what they do in Minecraft and that is take a 2d item and make a it 3d.
This:
to this:
Anyone have idea how I would do this without making a model in a seperate program
Well, if you have proper images with a nice contrast to the background, you could try to read the image's pixel value and contrast and try to find the outline of those images. As a next step, you would use Three.Shape or Three.Path and trace the outline with LineTo. Afterwards, you use an ExtrudeGeometry and extrude the shape into a 3d-object.
The main problem is finding the outline, i guess. This would only work with proper images and depending on the quality you want to achieve, you will have to implement the proper algorithms, see edge detection filters maybe.
Or being very simplistic, read the pixel values, if they are white or close to white, ignore them and if they are not, Draw another line.... something like that...