Trying To Make A Game, Need Help With Graphics - Topic

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Dec 27 2013 02:53pm

The problem i'm currently having is that i want to have a circle border, such that a certain part of it is shaded a different color , and it rotates around the entire circle

In this example, the red is the part that i want to rotate around the circle. What is the easiest approach?

Edit: This is in java

This post was edited by oOn on Dec 27 2013 02:54pm

carteblanche

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Dec 27 2013 05:29pm

there should be a drawArc method if memory serves.

Kronosaurus

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Jan 11 2014 11:06am

There are a lot of different approaches (if you're doing this with a basic drawing library). If you're not clearing the screen every frame, you could update the image by adding X pixels to the arc in the direction of rotation and removing X pixels from the arc on the opposite end

Code

moveArcClockwise(startAngle, endAngle, bigRadius, smallRadius)
for r between smallRadius and bigRadius:
drawPoint(r * cos(endAngle), r * sin(endAngle))
erasePoint(r*cos(beginAngle), r*sin(beginAngle))

in your picture, erase would just be to color blue and draw would be to color red

or just keep clearing the whole screen and redrawing a circle with an arc in it.

Code

drawCircleAndArc(startAngle, endAngle, bigRadius, smallRadius)
for angle between 0 and 360
color = blue
if angle between start and end angle
color = red

for r between smallRadius and bigRadius
drawPoint(r * cos(endAngle), r * sin(endAngle), color)

Hopefully this pseudo-code makes sense

This post was edited by Kronosaurus on Jan 11 2014 11:10am

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