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Why doesn't pickinfo.normal return -1, 0, or 1 only?


CrazyM
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Forgive me if this is a silly question, but my previous experience with collision normals is as follows:

 

collision on X should return Vec3(1,0,0)

collision on -X should return Vec3(-1,0,0)

collision on Y should return Vec3(0,1,0)

collision on -Y should return Vec3(0,-1,0)

collision on Z should return Vec3(0,0,1)

collision on -Z should return Vec3(0,0,-1)

 

Leadwerks pickinfo.normal returns a fraction depending on where on a face the collision occurs. Is pickinfo.face the "normal" function I'm used to, and maybe pickinfo.normal is describing the hit point?

 

If this is the case, how do you use pickinfo.face, I couldn't find much documentation on it?

 

Thanks!

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Your right, they are correct, it looks like the pickinfo.normal is describing the exact hit position, which is great for adding an impact particle effect at the location a hit occurs, though I wish pickinfo also had a separate return value that simply described the side of the hit. Good for geometric shape placement ;)

 

pickinfo.entity:GetPosition() + pickinfo.normal = exact hit position

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I agree with Rick. There are 3 vectors that you can use:

  • pickinfo:Entity:GetPosition(): the actual entities pivot position. For models this is often at the bottom of the model for instance.
  • pinkinfo.position: the actual point where the raycast hits something.
  • Pickinfo.normal: the direction perpendicular on the face that the raycast has hit

See the image below:

post-45-0-44981700-1409328466_thumb.jpg

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This is what I'm getting when camera picking the X face of a cube placed on the ground.

 

if (self.player.script.camera:Pick(mousePos.x, mousePos.y, pickinfo, pickradius, true)) then
   System:Print("Entity: " .. pickinfo.entity:GetPosition():ToString())
   System:Print("Position: " .. pickinfo.position:ToString())
   System:Print("Normal: " .. pickinfo.normal:ToString())
end

 

 

Entity: -3.000000, 1.000000, 0.000000

Position: -2.555588, 1.315765, -0.250583

Normal: 0.740685, 0.526274, -0.417638

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Okay, I made a much simpler script to try to eliminate any other potential causes. It's still not returning clean -1, 0, 1 values, but rather fractions.

 

Script.player = nil --entity "Player"
Script.reticle = "" --path "Reticle" "Tex file (*.tex):tex;"
window = Window:GetCurrent()
world = World:GetCurrent()
context = Context:GetCurrent()
pickradius = 0.1
pickinfo = nil
mousePos = nil
reticleOptic = nil
function Script:Start()
   pickinfo = PickInfo()
   reticleOptic = Texture:Load(self.reticle)
end
function Script:UpdateWorld()
   mousePos = window:GetMousePosition()
   if (self.player.script.camera:Pick(mousePos.x, mousePos.y, pickinfo, pickradius, true)) then
    if pickinfo ~= nil then
	    if pickinfo.entity:GetKeyValue("name") == "Block" then
		    --System:Print("Entity: " .. pickinfo.entity:GetPosition():ToString())
		    --System:Print("Position: " .. pickinfo.position:ToString())
		    System:Print("Normal: " .. pickinfo.normal:ToString())
	    end
    end
   end
end
function Script:PostRender(context)
   if reticleOptic ~= nil then
    context:SetColor(1,1,1,1)
    context:SetBlendMode(Blend.Alpha)	   
    context:DrawImage(reticleOptic, context:GetWidth()/2-32, context:GetHeight()/2-32, 64, 64)
    context:SetBlendMode(Blend.Solid)
   end   
end

 

Normal: -0.968764, -0.175351, 0.175352

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It's fairly close (wouldn't z be 0 and not 1 in what you are expecting since the normal would be pointing directly left or right pending on the side you click?). The rotation of the object is exactly 0,0,0 both in LE and the original modeling program? Is this a model or csg? If model try this with csg.

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In the example output above, the pick was from the -X side, it should have returned (-1,0,0). My test is using a grid aligned cube created in blender, it has a (0,0,0) rotation in the Leadwerks map. The problem does not exist when using a CSG, I am only able to create the problem with the Blender cube import. Interestingly, good values are returned from most of the face surface area from any face, but each face has a seemingly random spot that returns bad values. I have tried a default blender cube, which is off grid by default, with a center origin, a grid aligned blender cube with a center origin, and a grid aligned blender cube with a corner origin, they all produce the same result. I have no idea how a six sided cube can return different normal values from different areas of the same face.

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It must be something with blender - either via a setting when exporting or the exporter itself. When I created boxes using UU3D and exported as mdl, fbx binary, and fbx ascii, I am able to get the expected response for normals when the model is aligned to a global axis.

testboxes.zip

Win7 64bit / Intel i7-2600 CPU @ 3.9 GHz / 16 GB DDR3 / NVIDIA GeForce GTX 590

LE / 3DWS / BMX / Hexagon

macklebee's channel

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Thanks for posting that example test cubes. What I've discovered is that the bad normal values are only being returned on prefabs that are instantiated into the scene at runtime. If I place the block in the scene at design time, the normals are correct. I am setting the rotation to (0,0,0) on instantiation, but still getting the bad values. After trying your cubes, I tried my Blender cubes again and found the same thing, the Blender cube works fine when placed in the scene at design time, but not at runtime.

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