quaternion library - GameGuru Forum

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AmenMoses

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Joined: 20th Feb 2016

Location: Portsmouth, England

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Posted: 9th Dec 2016 21:30 Edited at: 12th Dec 2016 17:54

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To use just add the following to your script:

+ Code Snippet

	
if quat_lib == nil then
		quat_lib = require "scriptbank\\quaternions"
	end

Provides some useful quaternion functions.

Example of use:

+ Code Snippet


	local Ent = g_Entity[e]

	local xrot, yrot, zrot = Ent.anglex, Ent.angley, Ent.anglez
			
	q1 = EulerToQuat(math.rad(xrot), math.rad(yrot), math.rad(zrot))

	q2 = EulerToQuat(math.rad(15), 0, 0)

	q1 = QuatMul(q1, q2)

	local xr, yr, zr = QuatToEuler(q1)

	ResetRotation(e, math.deg(xr), math.deg(yr), math.deg(zr))

If none of that means anything to you then you probably don't need this.

I may add LERPs and SLERPs at some point, if anyone has a use for them.

Been there, done that, got all the T-Shirts!

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smallg

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Posted: 10th Dec 2016 09:56

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Could you use this to make a function to tell if the player is looking at something in all 3 angles?
If you can give it a modifiable leeway that would be great too.
Currently i only have a function that works for the y angle.

lua guide for GG
https://steamcommunity.com/sharedfiles/filedetails/?id=398177770
windows 10
i5 @4ghz, 8gb ram, AMD R9 200 series , directx 11

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AmenMoses

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Posted: 10th Dec 2016 10:24

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You could but its a bit over the top for that probably.

In my pickuppable script I work out where the real centre of an entity is (as an offset from the entities origin point) and store it. Then I work out where the player is looking (which only works in First Person, haven't figured it out for 3rd person yet) and check if that vector passes close to any entities centre (only need check those entities within a certain distance and 'in front') then I pick the closest entity of those.

When I've updated my scripts to incorporate quaternion math for the rotation aspects I'll post them all up here.

In the meantime here is the part that figures out if the player is looking at an entity:

function pickuppable_PlayerLookingAt (e, dist, fov)
	
	local Ent = g_Entity[e]
	local PlistEnt = g_pickuppable_list[e]
	
	if Ent == nil then return false end

dist = dist or 3000
	fov  = fov  or 1
		
	local Dx = (Ent.x + PlistEnt.xO) - g_PlayerPosX
	local Dz = (Ent.z + PlistEnt.zO) - g_PlayerPosZ
	local Dy = (Ent.y + PlistEnt.yO) - (g_PlayerPosY + 30)
	local sqr_dist = (Dx*Dx + Dy*Dy + Dz*Dz)
	
	if sqr_dist > dist*dist then return false end
	
	local function limitAngle (Angle)
		if Angle <= 0 then
		    Angle = 360 + Angle 
	    elseif Angle > 360 then
		    Angle = Angle - 360
		end
		return Angle
	end

local angleY = limitAngle(math.atan2(Dx, Dz) * (180.0 / math.pi))
	
	local pAng = g_PlayerAngY

while pAng < 0 or pAng > 360 do
		if pAng <= 0 then
			pAng = 360 + pAng
		elseif pAng > 360 then
			pAng = pAng - 360
		end
	end

local L = limitAngle(angleY - fov / 2)
	local R = limitAngle(angleY + fov / 2)
	
	if L < R and (pAng > L and pAng < R) or
	   L > R and (pAng > L or  pAng < R) then
	   
	   local PlayerVertAngle  = g_PlayerAngX
	   	-- Put this in because the angle appears to be behaving strangely 
		-- Up goes from 360 -> 280, Down goes 0 -> 85!
		if PlayerVertAngle < 280 then 
			PlayerVertAngle = -PlayerVertAngle
		else
			PlayerVertAngle = 2 * (360 - PlayerVertAngle)
		end

local EntAng = math.deg(math.asin(Dy/math.sqrt(sqr_dist)))
				
		return math.abs(EntAng - PlayerVertAngle) < fov / 2
	
	else
		return false
	end
end

+ Code Snippet

function pickuppable_PlayerLookingAt (e, dist, fov)
	
	local Ent = g_Entity[e]
	local PlistEnt = g_pickuppable_list[e]
	
	if Ent == nil then return false end

	dist = dist or 3000
	fov  = fov  or 1
		
	local Dx = (Ent.x + PlistEnt.xO) - g_PlayerPosX
	local Dz = (Ent.z + PlistEnt.zO) - g_PlayerPosZ
	local Dy = (Ent.y + PlistEnt.yO) - (g_PlayerPosY + 30)
	local sqr_dist = (Dx*Dx + Dy*Dy + Dz*Dz)
	
	if sqr_dist > dist*dist then return false end
	
	local function limitAngle (Angle)
		if Angle <= 0 then
		    Angle = 360 + Angle 
	    elseif Angle > 360 then
		    Angle = Angle - 360
		end
		return Angle
	end

	local angleY = limitAngle(math.atan2(Dx, Dz) * (180.0 / math.pi))
	
	local pAng = g_PlayerAngY

	while pAng < 0 or pAng > 360 do
		if pAng <= 0 then
			pAng = 360 + pAng
		elseif pAng > 360 then
			pAng = pAng - 360
		end
	end

	local L = limitAngle(angleY - fov / 2)
	local R = limitAngle(angleY + fov / 2)
	
	if L < R and (pAng > L and pAng < R) or
	   L > R and (pAng > L or  pAng < R) then
	   
	   local PlayerVertAngle  = g_PlayerAngX
	   	-- Put this in because the angle appears to be behaving strangely 
		-- Up goes from 360 -> 280, Down goes 0 -> 85!
		if PlayerVertAngle < 280 then 
			PlayerVertAngle = -PlayerVertAngle
		else
			PlayerVertAngle = 2 * (360 - PlayerVertAngle)
		end

		local EntAng = math.deg(math.asin(Dy/math.sqrt(sqr_dist)))
				
		return math.abs(EntAng - PlayerVertAngle) < fov / 2
	
	else
		return false
	end
end

Been there, done that, got all the T-Shirts!

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AmenMoses

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Posted: 12th Dec 2016 17:51

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Library updated to remove a wee buglet.

For those who may be interested here is the code that displays the 'jets' from the nozzles in my little moonlander demo

+ Code Snippet


function Show_Jets (q, x, y, z, xr, yr, zr)
	
	for k,_ in pairs(g_nozzles_list) do
		local noz = g_nozzles_list[k]
		
		local NX, NY, NZ = Rotate3D (noz.xo, noz.yo, noz.zo, xr, yr, zr)

		local qj = QuatMul(q, noz.q)
		local jxr, jyr, jzr = QuatToEuler(qj)
		
		ResetPosition(noz.e1, x - NX, y - NY, z - NZ)
		ResetRotation(noz.e1, math.deg(jxr), math.deg(jyr), math.deg(jzr))
		
		jxr, jyr, jzr = QuatToEuler(QuatMul(qj, q90))
		
		ResetPosition(noz.e2, x - NX, y - NY, z - NZ)
		ResetRotation(noz.e2, math.deg(jxr), math.deg(jyr), math.deg(jzr))
	end
end

Go on admit it, you thought it would be a lot longer than that didn't you?

Here is the code for the Rotate3D function:

+ Code Snippet

function RotatePoint2D (x, y, Ang)  -- Ang in radians
	local Sa, Ca = math.sin(Ang), math.cos(Ang)
	return x*Ca - y*Sa, x*Sa + y*Ca
end

function Rotate3D (x, y, z, xrot, yrot, zrot)  
	local NX, NY, NZ = x, y, z

	-- X
	NZ, NY = RotatePoint2D (NZ, NY, -xrot)
	
	-- Y
	NX, NZ = RotatePoint2D (NX, NZ, -yrot)
	
	-- Z
	NY, NX = RotatePoint2D (NY, NX, -zrot)

	return NX, NY, NZ
end

Someone might find it useful, the angles are in radians btw, pass in the x, y, z values (for example the offsets from centre of an entity to the entities rotation point) and the Euler angles (i.e math.rad(Entity,anglex) etc) and it will return back the rotated offsets, simply subtract them from the Entities x, y, z values to find the centre of the entity.

Been there, done that, got all the T-Shirts!

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Scripts / quaternion library

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