SetParent vs Atacch. Is Bug?

[Yue]

I am trying to put the case of my character having as reference the spindle of the nape of the neck, but it turns out that when he is falling into the void after a jump the case starts to float above his head, this using attach.

 

Now, if I use SetParent, to attach it to the mesh, whose root bone is in the middle of the legs, when falling the helmet does not move from its position.

 

 

In such a case I need to position it in the head, in the Neck bone, and I have found a partial solution. 

    function this:UpdateHelmet()

       

        helmet:SetPosition(0,0.12,-0.03)

        helmet:SetRotation(-20,0,0)

        helmet:Attach(ela,boneNeck)

       

    end

 

... self:UpdateHelmet() -- Run Ok.

 

[Josh]

Does this start happening when the player is falling at a fast speed? Does it get worse the faster they are falling?

[Yue]

2 hours ago, Josh said:

Does this start happening when the player is falling at a fast speed? Does it get worse the faster they are falling?

It happens after a jump, and gets worse when falling into the void.

[Josh]

13 minutes ago, Yue said:

It happens after a jump, and gets worse when falling into the void.

Okay, I think the bone attachment code is probably running one frame behind the physics update. I should be able to move the place this happens and it will fix the problem.

[Yue]

Lo tengo dentro del bucle, pero sigue al personaje en el hueso de la cabeza, pero va como si fuera un helicóptero helice d eun girando sobre el hueso de la cabeza.

 

[Josh]

I thought the problem was that the attached object was trailing one frame behind, but the test case I created shows it working perfectly at high speeds.

#include "UltraEngine.h"

using namespace UltraEngine;

int main(int argc, const char* argv[])
{
    //Get the displays
    auto displays = GetDisplays();

    //Create a window
    auto window = CreateWindow("Ultra Engine", 0, 0, 1280, 720, displays[0], WINDOW_CENTER | WINDOW_TITLEBAR);

    //Create a framebuffer
    auto framebuffer = CreateFramebuffer(window);

    //Create a world
    auto world = CreateWorld();

    //Create a camera
    auto camera = CreateCamera(world);
    camera->SetClearColor(0.125);
    camera->SetFov(70);
    camera->Move(0, 2, -8);
 
    //Create light
    auto light = CreateBoxLight(world);
    light->SetRotation(45, 35, 0);
    light->SetRange(-10, 10);
    
    //Model by PixelMannen
    //https://opengameart.org/content/fox-and-shiba
    auto model = LoadModel(world, "https://github.com/UltraEngine/Documentation/raw/master/Assets/Models/Characters/Fox.glb");
    model->SetScale(0.05);
    model->Animate(1);
    model->SetRotation(0, -90, 0);

    auto neck = model->skeleton->FindBone("b_Neck_04");
    auto head = model->skeleton->FindBone("b_Head_05");
    Vec3 rotation;

    //Model by alissvetlana
    //https://sketchfab.com/3d-models/hat-a7f54e87bea94730b4a1827ec1f770df
    auto hat = LoadModel(world, "https://github.com/UltraEngine/Documentation/raw/master/Assets/Models/Characters/hat.glb");
    hat->SetScale(0.025);
    hat->SetPosition(-0.3, 0.4, 0);
    hat->Attach(model, head);

    //Main loop
    while (window->Closed() == false and window->KeyHit(KEY_ESCAPE) == false)
    {
        float move = 0;
        if (window->KeyDown(KEY_RIGHT)) move += 1;
        if (window->KeyDown(KEY_LEFT)) move -= 1;
        model->Translate(move, 0, 0);
        light->Translate(move, 0, 0);
        camera->Translate(move, 0, 0);

        window->SetText(model->position.x);

        world->Update();

        rotation.y = Cos(float(Millisecs()) / 10.0f) * 65.0f;
        neck->SetRotation(rotation);

        world->Render(framebuffer);
    }
    return 0;
}

 

[Yue]

 Ok, it's something here as I'm doing things, these weirdos just happen to me.  The mesh I load it in a sequence inside a loop, but to make it work for me I have to do this.


And it only goes inside the loop.


 

function this:UpdateHelmet()

        if helmet and boneNeck then

            helmet:SetPosition(0, 0.12, -0.03)

            helmet:SetRotation(-20, 0, 0)

            helmet:Attach(ela,boneNeck)

        end

    end

 

    function this:UpdteBackpack()

        if backpack and boneBack then

            backpack:SetPosition(0, -0.1,0.1)

            backpack:SetRotation(0, 0, 0)

            backpack:Attach(ela,boneBack)

        end

    end

[Josh]

Are you attaching it every frame or just once?

[Yue]

In each frame, so that it does not move when it falls into the void.

[Josh]

That might be the cause of the problem. Maybe you should just attach it once?

[Yue]

But if I attach it only once, when falling into the void the helmet starts to rise and moves out of the character's position on his head. It is as if the controller is faster.

[Yue]

I have done this, and it seems to go well, that is to say that for attach to work correctly I have to use it inside the loop so that the case does not fall off when the character is falling.

I think maybe that's what makes it attach internally.

 

function this:UpdateHelmet()

 

        local posBone = boneNeck:GetPosition(true)

 

        local pos = TransformPoint(posBone,ela,nil)

 

        helmet:SetPosition(pos,true)

 

        local rotBone = boneNeck:GetQuaternion(true)

 

        local rot  = TransformRotation(rotBone,ela,nil)

 

        helmet:SetRotation(rot,true)

 

        --if helmet and boneNeck then

        --  helmet:SetPosition(0, 0, 0)

        --  helmet:SetRotation(0, 0, 0)

        --  helmet:Attach(ela,boneNeck)

        --end

    end

[Josh]

I need a working example I can run in order to test this.

[Yue]

I have sent the project by inbox.


Ficle Script Lua.  Player.lua. 
 

    function this:UpdateHelmet()

 

        local posBone = boneNeck:GetPosition(true)

 

        local pos = TransformPoint(posBone,ela,nil)

 

        helmet:SetPosition(pos,true)

 

        local rotBone = boneNeck:GetQuaternion(true)

 

        local rot  = TransformRotation(rotBone,ela,nil)

 

        helmet:SetRotation(rot,true)

 

        --if helmet and boneNeck then

        --  helmet:SetPosition(0, 0, 0)

        --  helmet:SetRotation(0, 0, 0)

        --  helmet:Attach(ela,boneNeck)

        --end

    end

 

    function this:UpdteBackpack()

        if backpack and boneBack then

            backpack:SetPosition(0, -0.1,0.1)

            backpack:SetRotation(0, 0, 0)

            backpack:Attach(ela,boneBack)

        end

    end

on start.

   self:UpdateHelmet()

        self:UpdteBackpack()

        self:UpdteHelmetWaist()

On Update. 

   self:UpdateHelmet() 

        self:UpdteBackpack()

        self:UpdteHelmetWaist()

[Josh]

I don't know how to make the bug appear.

I replaced UpdateHelmet with this code, and it works perfectly:

	function this:UpdateHelmet()
		--[[local posBone = boneNeck:GetPosition(true)
		local pos = TransformPoint(posBone,ela,nil)
		helmet:SetPosition(pos,true)
		local rotBone = boneNeck:GetQuaternion(true)
		local rot  = TransformRotation(rotBone,ela,nil)
		helmet:SetRotation(rot,true)]]
  
		if helmet and boneNeck and helmetattached ~= true then
			Notify("Attaching helmet now")
			helmetattached = true
			helmet:SetPosition(0, 0, 0)
			helmet:SetRotation(0, 0, 0)
			helmet:Attach(ela,boneNeck)
		end
	end

It also works fine if you attach the helmet each frame:

	function this:UpdateHelmet()
		helmet and boneNeck and helmetattached ~= true then
			--Notify("Attaching helmet now")
			--helmetattached = true
			helmet:SetPosition(0, 0, 0)
			helmet:SetRotation(0, 0, 0)
			helmet:Attach(ela,boneNeck)
		end
	end