75 lines
2.3 KiB
Standard ML
75 lines
2.3 KiB
Standard ML
signature CLICK_POINTS =
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sig
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val generate: int * int -> Real32.real vector
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val getClickPositionFromMouse: AppType.app_type
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-> (Real32.real * Real32.real) option
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val getDrawVec:
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Real32.real
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* Real32.real
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* Real32.real
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* Real32.real
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* Real32.real
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* AppType.app_type
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-> Real32.real vector
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end
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structure ClickPoints :> CLICK_POINTS =
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struct
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fun generate (start, finish) =
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let
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val difference = finish - start
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val increment = Real32.fromInt difference / 40.0
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val start = Real32.fromInt start
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in
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Vector.tabulate (41, fn idx => (Real32.fromInt idx * increment) + start)
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end
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(*
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* Range to detect from clickable position.
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* For example, if we have a clickable position at (x, y) = (500, 500),
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* with a range of 15, we can detect clicks targeting this position
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* from top left at (485, 485) to bottom right at (515, 515).
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* *)
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val range = 15.0
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fun getClickPos (clickPoints, mousePos, idx) =
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if idx = Vector.length clickPoints then
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NONE
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else
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let
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val curPos = Vector.sub (clickPoints, idx)
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in
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if mousePos < curPos - range orelse mousePos > curPos + range then
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getClickPos (clickPoints, mousePos, idx + 1)
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else
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SOME (Vector.sub (clickPoints, idx))
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end
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fun getClickPositionFromMouse (app: AppType.app_type) =
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case getClickPos (#xClickPoints app, #mouseX app, 0) of
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SOME xPos =>
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(case getClickPos (#yClickPoints app, #mouseY app, 0) of
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SOME yPos => SOME (xPos, yPos)
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| NONE => NONE)
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| NONE => NONE
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fun getDrawVec (xpos, ypos, r, g, b, app: AppType.app_type) =
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let
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val {windowWidth, windowHeight, ...} = app
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(* calculate normalised device coordinates *)
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val halfWidth = Real32.fromInt (windowWidth div 2)
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val halfHeight = Real32.fromInt (windowHeight div 2)
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val hpos = xpos - halfWidth
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val vpos = ~(ypos - halfHeight)
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(* coordinates to form small box around clicked area *)
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val left = (hpos - 5.0) / halfWidth
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val right = (hpos + 5.0) / halfWidth
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val bottom = (vpos - 5.0) / halfHeight
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val top = (vpos + 5.0) / halfHeight
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in
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Ndc.ltrbToVertex (left, top, right, bottom, r, g, b)
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end
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end
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