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POfinding xyz direction from rotation arround xyz
 

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    <p>I'm working on sort of a space shooter, where you can rotate your ship arround both x, y and z axis and thus shoot in any direction. To rotate the ship (I'm using openGL in c++), im rotating with 0-360 degrees arround either the x, y or z axis. The camera will always look the same direction (down along the z axis, like "default"). You simply look at the ship rotating.</p> <p>Example: glRotatef(-90.0f, 1.0f, 0.0f, 0.0f); The above example will rotate the ship -90 degrees arround the x axis. If the ship was pointing up along the positive y axis like in an ordinary space shooter before the roation, the ship would point inn along the negative z axis after the rotation.</p> <p>What I'm struggeling to figure out, is how to, at any time, be able to calculate the "direction" of the ship, and turn it into a vector3d (x, y, z inside a class called vector3d).</p> <p>I calculate the position (another vector3d, simply x, y and z) of any moving object by adding current position (x y z) to a velocity that I also store in a vector3d, and multiply it by delta time (time since last frame/update). When I shoot a projectile from the spaceship, I want to have the direction vector of the ship to use it as basis for the velocity of the projectile I'm shooting, so that I can calculate the position of the projectile the same way I calculate position of other objects by simply adding current projectile position to the velocity multiplied by deltatime.</p> <p>Since I have the direction of the ship on the form of rotation arround x, y and z, I figure it must be posible to somehow turn this into a vector3d that represents the same direction in a vector format (if that makes sence).</p>
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    1. COYou start with a Cartesian (x,y,z) vector representing the direction of the ship. As time goes by, you apply various rotations about the x, y, and z axes. What do you want to keep track of?
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    2. COI never actually have the xyz vector representing direction of the ship. The ship just starts off in origo, pointing the way the original vertexes paints it. In my case, the vertexes are put together so the ship "sits" on the xz plane, pointing towards negative z. Once I rotate it, I use the glRotatef function, which asks for an angle (0-360) and the axis you want to rotate arround. If you write glRotatef(180, 1.0f, 1.0f, 0.0f); you rotate 180 degrees arround x and y axis, but not z axis. This means I never actually have the xyz direction, only the xyz rotation.
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    3. CO@skakri: there is no absolute concept of direction, without you saying in which direction something faces at start, you cannot calculate this. imagine you draw not a spaceship but a sphere, what direction is that facing? You cannot know that unless you specify it at some point in time (usually in the initial draw).
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