Add vector helpers

1 files changed, 136 insertions, 0 deletions

diff --git a/builtin/vector.lua b/builtin/vector.lua
new file mode 100644
index 000000000..f534471c2
--- /dev/null
+++ b/builtin/vector.lua
@@ -0,0 +1,136 @@
+
+vector = {}
+
+function vector.new(a, b, c)
+	v = {x=0, y=0, z=0}
+	if type(a) == "table" then
+		v = {x=a.x, y=a.y, z=a.z}
+	elseif a and b and c then
+		v = {x=a, y=b, z=c}
+	end
+	setmetatable(v, {
+		__add = vector.add,
+		__sub = vector.subtract,
+		__mul = vector.multiply,
+		__div = vector.divide,
+		__umn = function(v) return vector.multiply(v, -1) end,
+		__len = vector.length,
+		__eq  = vector.equals,
+	})
+	return v
+end
+
+function vector.equals(a, b)
+	return a.x == b.x and
+	       a.y == b.y and
+	       a.z == b.z
+end
+
+function vector.length(v)
+	return math.hypot(v.x, math.hypot(v.y, v.z))
+end
+
+function vector.normalize(v)
+	return vector.divide(v, vector.length(v))
+end
+
+function vector.round(v)
+	return {
+		x = math.floor(v.x + 0.5),
+		y = math.floor(v.y + 0.5),
+		z = math.floor(v.z + 0.5)
+	}
+end
+
+function vector.distance(a, b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return math.hypot(x, math.hypot(y, z))
+end
+
+function vector.direction(pos1, pos2)
+	local x_raw = pos2.x - pos1.x
+	local y_raw = pos2.y - pos1.y
+	local z_raw = pos2.z - pos1.z
+	local x_abs = math.abs(x_raw)
+	local y_abs = math.abs(y_raw)
+	local z_abs = math.abs(z_raw)
+	if x_abs >= y_abs and
+	   x_abs >= z_abs then
+		y_raw = y_raw * (1 / x_abs)
+		z_raw = z_raw * (1 / x_abs)
+		x_raw = x_raw / x_abs
+	end
+	if y_abs >= x_abs and
+	   y_abs >= z_abs then
+		x_raw = x_raw * (1 / y_abs)
+		z_raw = z_raw * (1 / y_abs)
+		y_raw = y_raw / y_abs
+	end
+	if z_abs >= y_abs and
+	   z_abs >= x_abs then
+		x_raw = x_raw * (1 / z_abs)
+		y_raw = y_raw * (1 / z_abs)
+		z_raw = z_raw / z_abs
+	end
+	return {x=x_raw, y=y_raw, z=z_raw}
+end
+
+
+function vector.add(a, b)
+	if type(b) == "table" then
+		 return vector.new(
+			a.x + b.x,
+			a.y + b.y,
+			a.z + b.z)
+	else
+		return vector.new(
+			a.x + b,
+			a.y + b,
+			a.z + b)
+	end
+end
+
+function vector.subtract(a, b)
+	if type(b) == "table" then
+		return vector.new(
+			a.x - b.x,
+			a.y - b.y,
+			a.z - b.z)
+	else
+		return vector.new(
+			a.x - b,
+			a.y - b,
+			a.z - b)
+	end
+end
+
+function vector.multiply(a, b)
+	if type(b) == "table" then
+		return vector.new(
+			a.x * b.x,
+			a.y * b.y,
+			a.z * b.z)
+	else
+		return vector.new(
+			a.x * b,
+			a.y * b,
+			a.z * b)
+	end
+end
+
+function vector.divide(a, b)
+	if type(b) == "table" then
+		return vector.new(
+			a.x / b.x,
+			a.y / b.y,
+			a.z / b.z)
+	else
+		return vector.new(
+			a.x / b,
+			a.y / b,
+			a.z / b)
+	end
+end
+