Maths behind Pie Menu - math

Can someone explain to me what is the math behind this pie menu? I don't understand how it's rendered at all. Helps are appreciated

Most of graphics libraries have function like Pie for drawing of circular sector. To draw ring sector, like your bottom picture, one could draw all needed circular sectors with large radius, then circle or circular sector with lesser radius to fill center region.

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Marking overlapping paths with off-color borders

Say I have an image of a rose which I want to trace:
I construct a few curvature shapes with it's stroke weight set to 5 like so:
Say I'd now like to see which stroke is placed over another, is there any way for me to do so?
Say my bottom layered stroke crosses a top layered stroke, it then might draw two little lines across the stroke like so:
Is there any way to set up such functionality? Or mimic it? It would help work like this a ton.
The program could get the order of overlap right by looking at the layer orders, which you would of course have to manually order yourself. But having a feature that enables me to see which shape is on top of which when they're overlapping would be great.

How to move colored points from 2D image to 3D sphere

I have 2D color image. All colored points are located inside round area in center of this rectangle image, all points outside circle are black (I get these rectangle images from fisheye camera).
I know the coordinates of center of this circle and its radius.
I need to move all colored points from circle area on 2D image to the surface of sphere. More precisely hemisphere, because my camera has 180 degrees FOV.
My question is. How to move these colored points correctly? Will it be correct to just assign Z coordinate to all points inside circle area in accordance with sphere equation?
To make my question more clear I attached 2D image from my fisheye camera and image with desirable result.
First, you need the lens calibration data of your camera. Ocam or opencv will do a great job for you.
Second, as you mentioned that you already know your optical center, you can convert image coordinate into the sphere coordinate. So, now you have mapping function that maps image coordinate to sphere coordinate.
Third, you need some sort of rendering tool to observe your image mapped sphere. The simplest way is to use OpenGL. Map your texture on a sphere and move the camera inside the sphere.

css 3D transform cube perspective

I'm trying to create a grid of cubes that have a perspective that looks like you're looking at them from the top. Here is an example
http://imgur.com/elyJ5tu
This one is made by calculating how far the cube is from the middle and changing the border size. I want to make my own texture on the sides of the cube so I used CSS3 rotation to create the six sides of the cube and position them correctly to form a cube. Now I tried to recreate the effect by having the cubes tilt over the x and y axis depending on how far they are from the center and i got this:
http://codepen.io/anon/pen/yKmwg
As you can see it looks like they're on some kind of spherical surface. This is because the front and back side of the cube should not be rotating. Does anyone know of the proper way to do this. Thanks
Thank you #jozzas perspective origin was what i was looking for:
http://codepen.io/avovk/pen/yICrt

Getting coordinates by clicking over a circle overlay

I have a script that gets the coordinate of a map by clicking. At the same time, there are circle overlays spread across the map. I can get the coordinate of anywhere but the area covered by the overlays. What is a good work-around for this problem?
Either make the circles with {clickable: false} or capture the click event on the circles also

Show speedometer like needle with mschart

I need to create a chart looking like one shown in the image below using mschart. I can create the half circle using transparent color for the lower half of the doughnut chart, but i am unable to find way to show the needle.
The half circle is 100% and in the image the indicator is on 23%.
Also if there is another way to show the same information with mschart I can change the geography of the chart.

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