[spec/*,*] Split library in submodules.

rect.lua

@@ -0,0 +1,135 @@
+--- Axis-aligned rectangles.
+--
+-- Function for basic bounding rectangles building and testing.
+--
+-- @module gear.rect
+-- @copyright 2022 The DoubleFourteen Code Forge
+-- @author Lorenzo Cogotti
+
+local rotatesincos = require((...):gsub('rect', '')..'vec').rotatesincos
+
+local min, max = math.min, math.max
+local abs = math.abs
+
+local rect = {}
+
+
+--- Extend rectangle to include a point.
+function rect.expand(x,y,w,h, px,py)
+    if w < 0 or h < 0 then
+        return px,py,0,0
+    end
+
+    local xw, yh
+    x  = min(x, px)
+    y  = min(y, py)
+    xw = max(x+w, px)
+    yh = max(y+h, py)
+
+    return x, y, xw-x, yh-y
+end
+
+--- Calculate and return the union of two rectangles.
+function rect.union(x1,y1,w1,h1, x2,y2,w2,h2)
+    local xw1,yh1, xw2,yh2
+
+    if w1 < 0 or h1 < 0 then
+        local huge = math.huge
+
+        x1,y1,xw1,yh1 = huge,huge,-huge,-huge
+    else
+        xw1,yh1 = x1 + w1,y1 + h1
+    end
+    if w2 < 0 or h2 < 0 then
+        local huge = math.huge
+
+        x2,y2,xw2,yh2 = huge,huge,-huge,-huge
+    else
+        xw2,yh2 = x2 + w2,y2 + h2
+    end
+
+    x1  = min(x1, x2)
+    y1  = min(y1, y2)
+    xw1 = max(xw1, xw2)
+    xh1 = max(xh1, xh2)
+
+    return x1, y1, xw1 - x1, yh1 - y1
+end
+
+--- Calculate and return the intersection between two rectangles.
+function rect.intersection(x1,y1,w1,h1, x2,y2,w2,h2)
+    if w1 < 0 or h1 < 0 then
+        return x1,y1,w1,h1
+    elseif w2 < 0 or h2 < 0 then
+        return x2,y2,w2,h2
+    end
+
+    local xw1,yh1 = x1+w1, y1+h1
+    local xw2,yh2 = x2+w2, y2+h2
+
+    x1  = max(x1, x2)
+    y1  = max(y1, y2)
+    xw1 = min(xw1, xw2)
+    yh1 = min(yh1, yh2)
+    return x1,y1, xw1-x1,yh1-y1
+end
+
+--- Rotate rectangle around (ox,oy) about rot radians,
+--  and return the result's minimum enclosing
+--  axis-aligned rectangle.
+--
+-- NOTE: This causes precision loss, possibly generating
+--       larger bounds than needed for the rotated geometry
+--       Don't use this function repeatedly on the same bounds.
+function rect.rotate(rx,ry,rw,rh, rot, ox,oy)
+    if rw < 0 or rh < 0 then
+        return rx,ry,rw,rh
+    end
+
+    ox = ox or 0
+    oy = oy or 0
+
+    local sina,cosa = sin(rot),cos(rot)
+
+    local x1,y1 = rotatesincos(rx,    ry,    sina,cosa, ox,oy)
+    local x2,y2 = rotatesincos(rx+rw, ry,    sina,cosa, ox,oy)
+    local x3,y3 = rotatesincos(rx+rw, ry+rh, sina,cosa, ox,oy)
+    local x4,y4 = rotatesincos(rx,    ry+rh, sina,cosa, ox,oy)
+
+    local rxw, rxh
+    rx  = min(min(min(x1, x2), x3), x4)
+    ry  = min(min(min(y1, y2), y3), y4)
+    rxw = max(max(max(x1, x2), x3), x4)
+    ryh = max(max(max(y1, y2), y3), y4)
+
+    return rx,ry, rxw-rx,ryh-ry
+end
+
+--- Test whether point (x,y) lies inside a rectangle.
+function rect.pointinside(x,y, rx,ry,rw,rh)
+    return x >= rx and y >= ry and x-rx <= rw and y-ry <= rh
+end
+
+--- Test whether the first rectangle lies inside the second.
+function rect.rectinside(x1,y1,w1,h1, x2,y2,w2,h2)
+    return (x1 >= x2 and y1 >= y2 and w1 <= w2 and h1 <= h2 and w2 >= 0 and h2 >= 0)
+        or ((w1 < 0 or h1 < 0) and (w2 >= 0 and h2 >= 0))
+end
+
+--- Test two rectangles for equality with optional epsilon.
+function rect.eq(x1,y1,w1,h1, x2,y2,w2,h2, eps)
+    eps = eps or 0.007
+
+    return (abs(x1 - x2) <= eps and
+            abs(y1 - y2) <= eps and
+            abs(w1 - w2) <= eps and
+            abs(h1 - h2) <= eps)
+        or ((w1 < 0 or h1 < 0) and (w2 < 0 or h2 < 0))
+end
+
+--- Test whether a rectangle is empty.
+function rect.isempty(x,y,w,h)
+    return w < 0 or h < 0
+end
+
+return rect