Mesh won't rotate on a certain axis??

[joe1234]

There seems to be some issue with rotating a child mesh... Specifically a first person gun mesh. The way I have my FPS camera set up right now is like this: there's a playerHead node which parents the camera, cameraTarget, and playerWeapon mesh. Now looking around and everything works fine; all of playerHead's children follow its rotation and position just fine. But when I try to set a specific rotation for my gun mesh, I can only change its Y and Z rotation. If I try setting its X rotation... it just modifies the Z rotation. If I set both X and Z rotation, it actually adds the values together to rotate on the Z axis! What am I doing wrong? I've set my camera up a few different ways and its always the same. Rotations work fine when a mesh isn't a child, but as soon as I make it a child, its just unable to rotate on the X axis for some reason.

Help

[shadowslair]

If I`m not mistaken, when using a child all its transformations (position, rotation, scale) are relative to its parent`s, which in 99% is what we need, but probably this is causing you trouble. You can always get your head node`s position, rotation etc. and use them to position and rotate your weapon or whatever without using child&parent relationship. Just apply the transformations you need to your weapon after you`re done with the head node. Eventually (after you tried doing this yourself ) you can post some code, because there`s a plenty of things you potentially may be doing wrong. Sometimes it`s a good idea to stop investigating using the trial-and-failure method and try to figure out what you are doing.

[joe1234]

If I`m not mistaken, when using a child all its transformations (position, rotation, scale) are relative to its parent`s, which in 99% is what we need, but probably this is causing you trouble.

Nooo no no, that's what I'm wanting. What I'm trying to do is make the weapon aim just a bit downward instead of straight forward from the head/camera's point of view. But it seems that I can only roll the weapon, or rotate it to the left or right. Up and down just doesn't seem to work.

Code: Select all

	// Init variables
	IAnimatedMesh* mesh = smgr->getMesh("stupidgun (2).3ds");
	IAnimatedMesh* mesh2 = smgr->getMesh("cube.3ds");
	ICameraSceneNode* cam = smgr->addCameraSceneNode(0, vector3df(0,0,-20), vector3df(0,0,0));
	IAnimatedMeshSceneNode* weapon = smgr->addAnimatedMeshSceneNode(mesh);
	IAnimatedMeshSceneNode* playerHead = smgr->addAnimatedMeshSceneNode(mesh2);
	IAnimatedMeshSceneNode* camTarget = smgr->addAnimatedMeshSceneNode(mesh2);

	// Set parents
	cam->setParent(playerHead);
	weapon->setParent(playerHead);
	camTarget->setParent(playerHead);

	// Set some other stuff
	if (weapon) weapon->setMaterialTexture(0, driver->getTexture("derp.bmp"));
	playerHead->setPosition(vector3df(10,10,10));
	playerHead->setRotation(vector3df(0,0,0));
	camTarget->setPosition(vector3df(0,0,100));
	cam->setPosition(vector3df(0,0,5));
	cam->setTarget(camTarget->getAbsolutePosition());
	weapon->setPosition(vector3df(6,-3,20));
	weapon->setRotation(vector3df(0,-90,0)); // <--- ***This is the problem***
	smgr->addLightSceneNode(0, vector3df(0,0,0), SColor(0,1,0,0), 800);
	float mouse_sens = 0.1f;

	// Game loop *****
	while(device->run())
	{
		vector3df position = playerHead->getPosition();
		vector3df rotation = playerHead->getRotation();
		if (keyboard.IsKeyDown(KEY_KEY_W)) position.Z += 0.02f;
		if (keyboard.IsKeyDown(KEY_KEY_S)) position.Z -= 0.02f;
		if (keyboard.IsKeyDown(KEY_KEY_D)) position.X += 0.02f;
		if (keyboard.IsKeyDown(KEY_KEY_A)) position.X -= 0.02f;
		if (keyboard.IsKeyDown(KEY_UP)) rotation.X -= mouse_sens;
		if (keyboard.IsKeyDown(KEY_DOWN)) rotation.X += mouse_sens;
		if (keyboard.IsKeyDown(KEY_RIGHT)) rotation.Y += mouse_sens;
		if (keyboard.IsKeyDown(KEY_LEFT)) rotation.Y -= mouse_sens;
		if (rotation.X < -89.9f) rotation.X = -89.9f;
		if (rotation.X > 89.9f) rotation.X = 89.9f;
		playerHead->setPosition(position);
		playerHead->setRotation(rotation);
		cam->setTarget(camTarget->getAbsolutePosition());
		driver->beginScene(true, true, SColor(255,140,255,255));
		smgr->drawAll();
		guienv->drawAll();
		driver->endScene();
	}

So my problem is if I change weapon's X or Z rotation value (after making it a child of playerHead), it just rolls, and the Y value rotates it left and right. But I want up and down. (And this is all based off the camera's viewpoint)

:?::?::?::?:

[shadowslair]

Too lazy reading and thinking, but here are a few quick guesses:

1) If all you need is to position and rotate your weapon in the beginning and don`t apply any local transformations any further, why don`t you simply position and rotate your weapon model from within your modelling program?

2) Try rotating your weapon before making it child of the head.

3) If you use "weapon->setRotation(vector3df(0,-90,0));" just to make your weapon point forward, it`s much better to do this in the modelling program, because you`re changing its orientation axes. Keep in mind that Irrlicht and every other engine rotates a node first on X, second on Y, and last on Z. Probably this is causing you trouble.

Hope this helps.

[hybrid]

IIRC, Irrlicht rotates in the order Z, Y, X.

[shadowslair]

Oops, my mistake. I kinda figured this out 6 months ago when I had to change the rotation axes` sequence getting proper realtime rotations using some 3ds Max biped bone coordinate systems.
All I tried to point out was that rotating a mesh 90 degrees this way affects it`s rotations around the other axes. I think this is what I get for trying way too many eninges for the last years.

[joe1234]

Well, that appears to have fixed it. I changed its rotation in Blender and re-exported it; it seems to be working now. Though I'm still confused as to why I had a problem in the first place. I mean why would spinning it -90 degrees in one direction essentially break the other two directions? Its as if one direction was relative and the other was absolute... !

Oh well, it works for now. Thanks for the help guys! Appreciate it!