want to make a horizontal compass

[havenphillip]

I want to make a horizontal compass that allows the player to navigate towards a goal. How can I set the rotation towards the goal to equal zero so that whenever the player is facing the objective it is set at the middle?

[macklebee]

I can't tell from your post if you have a horizontal compass working or not, which is somewhat independent from finding the angle between a player and a target in relation to the player's direction. If you are asking to get the horizontal compass working, calculate the relative angle, and also make the target show up on the compass as well, then this will be a fairly large discussion. And it's another reason why the techass forum is garbage, if this will be a lengthy discussion about multiple things regarding drawing a hud, calculating the relative angle, etc instead of one just concise question about one facet.

In any case, if you are just wanting to calculate the relative angle, then you have to calculate the angle between the player and the target based on their global positions, determine the Y-rotation of the player, and then subtract the two.

Example script:

Script.player = "" --entity "Player Entity"
Script.target = "" --entity "Target Entity"
Script.angle = 0

function PerfectAngle(pos1,pos2)
	local dx, dz
	dx = pos2.x - pos1.x
	dz = pos2.z - pos1.z
	return Math:ATan2(dx,dz)
end

function NormalizeAngle(angle)
	if angle <= 0 then
		return angle + 360
	else
		return angle
	end
end

function Script:UpdateWorld()
	self.perfectangle = PerfectAngle(self.player:GetPosition(true),self.target:GetPosition(true))
	self.angle = self.player:GetRotation(true).y - self.perfectangle
end

function Script:PostRender(context)
	context:SetBlendMode(Blend.Alpha)
	context:DrawText(string.format("Angle between Player to Target: %.0f",NormalizeAngle(self.angle)),2,22)
	context:SetBlendMode(Blend.Solid)
end

Place a pivot into a scene and attach this script. Drag the Player and Target entities into the Script's Property dialog and run the game.

[havenphillip]

Oh awesome! That's exactly what I was looking for. I only need to do this and some PostRender() stuff but this is right.

function NormalizeAngle(angle)
    if angle <= - 180 then
        return angle + 360
    elseif angle >= 180 then
        return angle - 360
    else
        return angle + 0
    end
end

Here it is. Working perfectly:
 

UI Elements.zip