Screen to world coordinates?

[TheDoctorWho 0]

I'm trying to fire a projectile at where ever the center of the screen is, but I can't figure out how to get the coords of that position.

 

I need the opposite of GRAPHICS::_WORLD3D_TO_SCREEN2D. Does a function for this exist, or does anyone know how else to do it?

[alex8b 29]

Up!

[CamxxCore 156]

Up!

 

Here is a very easy to follow article that appears to cover this..

 

http://www.flipcode.com/archives/Plotting_A_3D_Point_On_A_2D_Screen.shtml

[alex8b 29]

 

		public static Vector3 ScreenRelToWorld(Vector3 camPos, Vector3 camRot, Vector2 coord)
		{			
			var camForward = RotationToDirection(camRot);
			var rotUp = camRot + new Vector3(10, 0, 0);
			var rotDown = camRot + new Vector3(-10, 0, 0);
			var rotLeft = camRot + new Vector3(0, 0, -10);
			var rotRight = camRot + new Vector3(0, 0, 10);

			var camRight = RotationToDirection(rotRight) - RotationToDirection(rotLeft);
			var camUp = RotationToDirection(rotUp) - RotationToDirection(rotDown);

			var rollRad = -DegToRad(camRot.Y);

			var camRightRoll = camRight * (float)Math.Cos(rollRad) - camUp * (float)Math.Sin(rollRad);
			var camUpRoll = camRight * (float)Math.Sin(rollRad) + camUp * (float)Math.Cos(rollRad);

			var point3D = camPos + camForward * 10.0f + camRightRoll + camUpRoll;
			Vector2 point2D;
			if (!WorldToScreenRel(point3D, out point2D)) return camPos + camForward * 10.0f;
			var point3DZero = camPos + camForward * 10.0f;
			Vector2 point2DZero;
			if (!WorldToScreenRel(point3DZero, out point2DZero)) return camPos + camForward * 10.0f;

			const double eps = 0.001;
			if (Math.Abs(point2D.X - point2DZero.X) < eps || Math.Abs(point2D.Y - point2DZero.Y) < eps) return camPos + camForward * 10.0f;
			var scaleX = (coord.X - point2DZero.X) / (point2D.X - point2DZero.X);
			var scaleY = (coord.Y - point2DZero.Y) / (point2D.Y - point2DZero.Y);
			var point3Dret = camPos + camForward * 10.0f + camRightRoll * scaleX + camUpRoll * scaleY;
			return point3Dret;
		}

                public static Vector3 RotationToDirection(Vector3 rotation)
		{
			var z = DegToRad(rotation.Z);
			var x = DegToRad(rotation.X);
			var num = Math.Abs(Math.Cos(x));
			return new Vector3
			{
				X = (float)(-Math.Sin(z) * num),
				Y = (float)(Math.Cos(z) * num),
				Z = (float)Math.Sin(x)
			};
		}

 

Edited July 25, 2015 by alex8b

[alex8b 29]

 

Up!

 

Here is a very easy to follow article that appears to cover this..

 

http://www.flipcode.com/archives/Plotting_A_3D_Point_On_A_2D_Screen.shtml

 

 

1. The math there is wrong and doesn't cover camera parameters.

2. We need 2d ->3d not 3d->2d