Align node to terrain

[JhimBhoy]

Hello everyone,

Im trying to align a node to the terrain so it looks like a fighter plane at very low level following the curves and banks of the terrain.

I'm totally new to Irrlicht and 3D maths so sorry if this is a blindingly stupid question. I've searched the forums for the answer and I thought arras 'free flight' functions were the answer.

Code: Select all

Removed old code

The weird thing is it works for short distances - I'm thinking perhaps there is a limit to how much you can rotate at one time. I've honestly no idea

Is there a way to align the node to the terrain and I'm just going about it the wrong way?

Thanks in advance

[JhimBhoy]

Ok.

I've got yaw and roll to work by using an empty parent node to control the position and yaw and the main player node to control roll.

I then added a grandparent empty node to control pitch.

This doesn't work unfortunately.

Here's the code:

Code: Select all

	
        // set up previous rotation state
	float old_yaw=0, old_pitch=0, old_roll=0;

	while(device->run())
	if (device->isWindowActive())
	{
		if (quit)
		{
			device->closeDevice();
		}
		
		// Get delta time
		irr::u32 now = timer->getTime();
		delta_time = (now - then) / 1000.f;
		then = now; 

		get_input();

		player1.x+=sin(player1.dir*core::DEGTORAD)*(player1.speed*delta_time);
		player1.z+=cos(player1.dir*core::DEGTORAD)*(player1.speed*delta_time);

		// position fighter
		float yaw=player1.dir;
		float fighter_z=player1.z;
		float fighter_x=player1.x;
		float fighter_h=terrain->getHeight(fighter_x,fighter_z);
		fighter_grandparent->setPosition(core::vector3df(player1.x,fighter_h+80,player1.z));
		fighter->setPosition(core::vector3df(0,0,0));

		// get heights at wing tips
		float l = 80.0f; // length of ship/2
		float w = 40.0f; // width of ship/2
		float bx_yaw=yaw+90;
		if (bx_yaw>359) bx_yaw-=360;
		float bx1_x=fighter_x+sin((bx_yaw)*core::DEGTORAD)*w;
		float bx1_z=fighter_z+cos((bx_yaw)*core::DEGTORAD)*w;
		float bx2_x=fighter_x+sin((bx_yaw)*core::DEGTORAD)*-w;
		float bx2_z=fighter_z+cos((bx_yaw)*core::DEGTORAD)*-w;
		float z1 = terrain->getHeight(bx1_x,bx1_z);
		float z2 = terrain->getHeight(bx2_x,bx2_z);

		// get heights at nose/tail
		float bx3_x=fighter_x+sin((yaw)*core::DEGTORAD)*l;
		float bx3_z=fighter_z+cos((yaw)*core::DEGTORAD)*l;
		float bx4_x=fighter_x+sin((yaw)*core::DEGTORAD)*-l;
		float bx4_z=fighter_z+cos((yaw)*core::DEGTORAD)*-l;
		float x1 = terrain->getHeight(bx3_x,bx3_z);
		float x2 = terrain->getHeight(bx4_x,bx4_z);	
		
		// calc roll and pitch values
		float roll = atan(z1/40-z2/40)*core::RADTODEG; // the division is to compensate for scaling
		float pitch = atan(x2/40-x1/40)*core::RADTODEG;

		// get relative rotations
		float yaw_offset=yaw-old_yaw;
		float pitch_offset=pitch-old_pitch;
		float roll_offset=roll-old_roll;
		
		turn_ship(fighter_parent,yaw_offset);
		roll_ship(fighter,roll_offset);		
		pitch_ship(fighter_grandparent,pitch_offset);
	
		old_yaw=yaw;
		old_roll=roll;
		old_pitch=pitch;
		
		// position camera
		float cam_x=player1.x+(sin(player1.dir*core::DEGTORAD)*-600);
		float cam_z=player1.z+(cos(player1.dir*core::DEGTORAD)*-600);
		float cam_y=terrain->getHeight(cam_x,cam_z);
		
		float cam_diff=fighter_h-cam_y;
		float cam_target_x=sin(player1.dir*core::DEGTORAD)*(450+cam_diff);
		float cam_target_z=cos(player1.dir*core::DEGTORAD)*(450+cam_diff);
		camera->setPosition(core::vector3df(cam_x,cam_y+400,cam_z));
		camera->setTarget(core::vector3df(player1.x+(cam_target_x),cam_y+50,player1.z+(cam_target_z)));
		camera->updateAbsolutePosition();

		driver->beginScene(true, true, 0 );

		smgr->drawAll();
		env->drawAll();

		driver->endScene();

		// display frames per second in window title
		int fps = driver->getFPS();
		if (lastFPS != fps)
		{
			core::stringw str = L"Advanced Tactical Fighter - Demo [";
			str += driver->getName();
			str += "] FPS:";
			str += fps;
			str += "   ";

			device->setWindowCaption(str.c_str());
			lastFPS = fps;
		}
	}

	device->drop();
	
	return 0;
}

// Act on input
bool get_input()
{
		if (keys[irr::KEY_KEY_W] || keys[irr::KEY_UP])
		{
			player1.speed+=400*delta_time;
			if (player1.speed>1000) player1.speed=1000;
		}
		if (keys[irr::KEY_KEY_S] || keys[irr::KEY_DOWN])
		{
			player1.speed-=400*delta_time;
			if (player1.speed<-1000) player1.speed=-1000;
		}
		if (keys[irr::KEY_KEY_A] || keys[irr::KEY_LEFT])
		{
			player1.dir-=player1.turn_rate*delta_time;
			if (player1.dir<0) player1.dir+=360;
		}
		if (keys[irr::KEY_KEY_D] || keys[irr::KEY_RIGHT])
		{
			player1.dir+=player1.turn_rate*delta_time;
			if (player1.dir>359) player1.dir-=360;
		}

		return false;
}

void init_player()
{
	player1.x=2942;
	player1.y=0;
	player1.z=4143;
	player1.dir=0;
	player1.speed=0;
	player1.turn_rate=30;
}
//--- rotate node relative to its current rotation -used in turn,pitch,roll ---
void rotate(irr::scene::ISceneNode *node, irr::core::vector3df rot)
{
	irr::core::matrix4 m;
    m.setRotationDegrees(node->getRotation());
    irr::core::matrix4 n;
    n.setRotationDegrees(rot);
    m *= n;
    node->setRotation( m.getRotationDegrees() );
    node->updateAbsolutePosition(); 
}

//--- turn ship left or right ---
void turn_ship(irr::scene::ISceneNode *node, irr::f32 rot)
{
    rotate(node, irr::core::vector3df(0.0f, rot, 0.0f) );
}

//--- pitch ship up or down ---
void pitch_ship(irr::scene::ISceneNode *node, irr::f32 rot)
{
    rotate(node, irr::core::vector3df(rot, 0.0f, 0.0f) );
}

//--- roll ship left or right ---
void roll_ship(irr::scene::ISceneNode *node, irr::f32 rot)
{
    rotate(node, irr::core::vector3df(0.0f, 0.0f, rot) );
}

Anyone any ideas? I think I need to use quaternions but my 3D math is rubbish and I've barely understood 3D vectors.

This is probably really obvious and I just need a pointer in the right direction.

Here is a video of it running with yaw and roll:
http://www.youtube.com/watch?v=5EFzUC5PcpE

[sudi]

i digged out some old solution i gave to someone.

http://irrlicht.sourceforge.net/phpBB2/ ... hp?t=29529

that topic should help all relevant code is inside that topic.

[JhimBhoy]

I'll give this a go.

Thank you Sudi