Captain07 Posted February 2, 2021 Share Posted February 2, 2021 Hello, I'm working with circles (dxDrawCircle) recently and I need a function to check if the player's cursor is within a circle's sector (a button). Is there a function to do this? I found the isMouseInCircle function, but it's not enough. Any ideas? Link to comment

MRmihailZH Posted February 2, 2021 Share Posted February 2, 2021 (edited) use a triple check, first whether the cursor is in a large circle, then whether the cursor is in a small circle, and whether the cursor is in a triangle x, y - cursor coordinates x1, y1, x2, y2, x3, y3 - coordinates of the angles of the triangle the function returns true if the point x, y belongs to a triangle function getPosition(x, y, x1, y1, x2, y2, x3, y3) local k = (x1 - x) * (y2 - y1) - (x2 - x1) * (y1 - y) local m = (x2 - x) * (y3 - y2) - (x3 - x2) * (y2 - y) local n = (x3 - x) * (y1 - y3) - (x1 - x3) * (y3 - y) return ((k >= 0 and m >= 0 and n >= 0) or (k <= 0 and m <= 0 and n <= 0)) end Edited February 2, 2021 by MRmihailZH 1 Link to comment

Captain07 Posted February 2, 2021 Author Share Posted February 2, 2021 Thanks, I'll check it out! Link to comment

Discord Moderators Zango Posted February 2, 2021 Discord Moderators Share Posted February 2, 2021 If you only want to see if the point is inside one of the circle's quadrants, it can be done really simple. If you want to check for any sector, I have made the following, where you define the sector from two angles. It would also be possible to define the sectors from vectors instead. local sx, sy = guiGetScreenSize( ) function isMouseInCircleSector(cx, cy, r, angleStart, angleEnd) local mx, my = getCursorPosition() if not mx then return end -- Relativise mouse position to circle center mx = mx * sx - cx my = my * sy - cy -- Convert angles to vectors local x1, y1 = r * math.cos(angleStart), r * math.sin(angleStart) local x2, y2 = r * math.cos(angleEnd), r * math.sin(angleEnd) return mx^2 + my^2 <= r^2 and -- Check if within radius -x1*my + y1*mx <= 0 and -- Check if counterclockwise to angleStart -x2*my + y2*mx > 0 -- Check if clockwise to angleEnd end Where: cx, cy = Circle center r = Circle radius angleStart = start of sector, in radians angleEnd = end of sector, in radians So as an example, here are the angleStart and angleEnd values for each quadrant 270, 0 - First quadrant 180, 270 - Second quadrant 90, 180 - Third quadrant 0, 90 - Fourth quadrant Hope it's useful 1 Link to comment

Captain07 Posted February 2, 2021 Author Share Posted February 2, 2021 Thank you! I tested it and for some reason it's not working properly, did I mess something up? I wanted make it green when it's within the sector, otherwise red. -- 1st test if isMouseInCircleSector(sx/2, sy/2, 330, 0, 90) then dxDrawCircle(sx/2, sy/2, 330, 0, 90, tocolor(0, 255, 0, 255)) else dxDrawCircle(sx/2, sy/2, 330, 0, 90, tocolor(255, 0, 0, 255)) end -- 2nd test if isMouseInCircleSector(sx/2, sy/2, 330, 0, 180) then dxDrawCircle(sx/2, sy/2, 330, 0, 180, tocolor(0, 255, 0, 255)) else dxDrawCircle(sx/2, sy/2, 330, 0, 180, tocolor(255, 0, 0, 255)) end https://imgur.com/a/g6udD5L Link to comment

Discord Moderators Zango Posted February 2, 2021 Discord Moderators Share Posted February 2, 2021 You need to parse radians to it, like this isMouseInCircleSector(sx/2, sy/2, 330, math.rad(0), math.rad(90)) 1 Link to comment

Captain07 Posted February 2, 2021 Author Share Posted February 2, 2021 Oops... thanks! Now it's working like a charm! 1 Link to comment

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