Drawing primitives like line, circle, polygon, nurbs in iOS - ios

Are there any 3d engines for iOS that have a good set of APIs for drawing primitives such as lines, circle, rectangle, maybe even nurbs?
AFAIK, Irrlicht has a set functions to draw lines and rectangles, but that is it..
Specifically looking for something inside 3d engines so that it is easy to render and visualize 3d models plus provides a mechanism to add primitives to these 3d models on the fly.

Here are a few 3D game engines. Try using one of them:
SIO2 is pretty nice http://sio2interactive.com/
Unity3D has iOS support
Shiva3D (havent tried it out personally)
Check this link out as well.

Related

How to make custom camera lens effects in ios

I am not an ios developer but my client wants me to make an iphone app like
https://itunes.apple.com/us/app/trippy-booth-amazing-filterswarps/id448037560?mt=8
I have seen some custom library like
https://github.com/BradLarson/GPUImage
but do not find any camera lens customization example.
any kind of suggestions would be helpful
Thanks in advance
You can do it through some custom shader written in OpenGL(or metal just for iOS), then you can apply your shader to do interesting stuff like the image in above link.
I suggest you take a look at how to use the OpenGL framework in iOS.
Basically the flow would like:
Use whatever framework to capture(even in real time) a image.
Use some framework to modify the image. (The magic occur here)
Use another stuff to present the image.
You should learn how to obtain a OpenGL context, draw a image on it, write a custom shader, apply the shader, get the output, to "distort the image". For real, the hardest part is how to create that "effect" in your mind by describing it using a formula.
This is quite similar to the photoshop mesh warp (Edit->Transform->Warp). Basically you treat your image as a texture and then you render it on to a mesh (Bezier Patch) that is a grid that has been distorted into bezier curves, but you leave the texture coordinates as if it was still a grid. This has the effect of "pulling" the image towards the nodes of the patch. You can use OpenGL (GL_PATCHES) for this; I imagine metal or sceneKit might work as well.
I can't tell from the screen shots but its possible that the examples you reference are actually placing their mesh based on facial recognition. CoreImage has basic facial recognition to give youth out and eye positions which you could use to control some of the nodes in your mesh.

How to create a hole in the box in SceneKit?

I'm using SceneKit to create a 3D Room for a Swift iOS app.
I'm using multiple boxes and placing it together to create different walls of the room. I want to also add doors and windows to the room for which I need to cut holes into the walls. This looks like a very common scenario but yet I couldn't find any relevant answers out there.
I know there are multiple ways of doing it -
Simplest being, don't cut the box. Place another box with door or wall texture.
But I do want to keep a light source outside of the room and want it to flow into the room through these doors and windows
Create multiple boxes for single wall and put them together to make a geometry
My last resort maybe.
Create custom geometry.
Feels too complicated since it requires me to draw each triangle myself. Not sure?
But what I was actually expecting -
Subtract geometries from geometries?
Library that's already handling these complexities?
Any pointers would be very helpful.
Thanks.
Scene kit offers some awesome potential but it's not a substitute for a 3D modeling program. If you want something much beyond assembling with primitives and extrusion in a plane you should think about constructing your model in a dedicated 3-D package and exporting the model into SceneKit as a .dae file. You might take a look at Blender. It's free and readily available on the net. I suspect it can easily do what you want and the learning curve will be compensated by the higher level functions of a graphics program versus coding.
I think #bpedit described the best approach.
A weak second choice would be to use SCNShape to build your geometry. That still leaves you the problem of constructing a Bezier path that matches your wall layout/topology. That might be a helpful hack in the short term, to save you from an immediate learning curve in modeling software. But I predict you'll still eventually move to a tool like Blender, SketchUp, Cheetah 3D, or Maya.

How can I draw this complex shape using iOS Quartz 2D drawing?

I know how to draw simple shapes - rectangles, ellipses and lines etc. using iOS Quartz 2D drawing.
Just now I'm trying to draw a relatively complex shape though, the tail of a musical quaver:
Can anybody suggest a good way to approach this problem?
Can you design the quaver in a graphics program like Inkscape, export as an SVG, and then render using SVGKit? From a development level, it would be much easier to maintain something that you can visually update, rather than trying to draw a shape with code.
What I have learned from my designers is, that you start with a simple form and then extend and change it in single, small steps. Sometime later you arrive at the complex form. So, like answered by #Duncan C building a path. Now I know that is quite tedious. One alternative not mentioned here is PaintCode, an app that produces Cocoa code from your drawing. It is called PaintCode and should do what you want. Btw I am not affiliated with the makers of PaintCode!
You could draw that as a filled UIBezierPath (which is a UIKit wrapper on a CGPath).
You'd open a path, draw a sequence of straight lines and cubic or quadratic bezier curves, then close the path. Then you'd draw it as a filled path.
Once you have the path created, you could draw it with a single call.
A couple of alternatives, as Duncan seems to have answered this.
One option would be to dynamically scale a high resolution image.
There is one caveat with this approach: you should not scale anything below 1/2 of the original size, otherwise the interpolation tends to glitch.
So you would need to store image at say 64x64, 128x128, 256x256 etc
You could pack all of these into a single 256x512, and this is what a lot of games do.
Another option is to render a quaver unicode character http://www.fileformat.info/info/unicode/char/266a/index.htm

Displaying a tiled map with 3D objects on top of it

I needed to display tiled world map with small 3D building models on top of it.
I can see two possible approaches here:
Display tiled map with Route-Me or similar (btw what similar tiled map controls you can suggest?). Then place transparent (I don't know if that is possible) OpenGL surface over it and render buildings here.
Display both tiles and buildings using OpenGL.
I don't need any extra features. Just panning tiled map (by touch or by performing selector) and displaying many small buildings (needed to handle tap on buildings) over it.
I don't know what approach is best and easier/faster to produce. I'll be very happy to get some information about how to produce them (especially 2nd one).
If you know some way with less efforts then please let me know.
Approach two is probably the best but your question is very vague, to properly answer this you would need a lot of different requirements some even too specific to answer.
How I would go about producing this approach would be to use OpenGL and setup two different 'world' matrices. One for the 2D tiled map and one for the 3D buildings that would go on top of it. (Yes transparency is possible in OpenGL.)
Make sure you aren't starting out too big for a project! Good luck!

How can I create a corner pin effect in XNA 4.0?

I am trying to write a strategy game using XNA 4.0, with a dynamically generating map, and it's really difficult to create all the ground textures, having to distort them individually in photoshop.
So what I want to do is create a flat image, and then apply the distortion programatically to simulate perspective, by moving the corners of the image.
Here is an example done in photoshop:
How can I do that in XNA?
My answer isn't XNA-specific as I've never actually used the library; however the concept should still apply.
In general, the best way to get a good perspective effect is to actually give 3d coordinates and transformations and let DirectX/OpenGL handle the rest. This has great benefits over attempting to do it yourself - specifically, ease of use, performance (much of the work is passed on to your graphics card), and perspective-correct texturing. And nothing's stopping you from doing 3d and 2d in the same scene, if that's a concern. There are numerous tutorials online for getting set up in the third dimension with XNA. I'd suggest heading over to MSDN.

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