20,741
edits
Canvas Nasal API: Difference between revisions
Jump to navigation
Jump to search
→createTransform: http://flightgear.org/forums/viewtopic.php?f=71&t=18727#p174003
m (→createTransform: http://flightgear.org/forums/viewtopic.php?f=71&t=18727#p173971) |
(→createTransform: http://flightgear.org/forums/viewtopic.php?f=71&t=18727#p174003) |
||
| Line 112: | Line 112: | ||
| 0 || 0 || 1 | | 0 || 0 || 1 | ||
|} | |} | ||
You should probably change the order of creating the transforms for pitch and roll as normally one would rotate first and then move according to roll and then move according to pitch up and down. Keep in mind that rotations always happens around the origin of the local coordinate frame of the object being rotated. For a rotation around another point you would need to move the object first until the center coincides with the local origin then rotate and afterwards move back. Instead of applying three transformations there exists a shortcut to pass the center of rotation as second argument to setRotation. | |||
To further shorten the code an especially to allow rotating objects imported from SVG there exists setRotation also for canvas Elements (not only Transformation) and additionally setCenter which instead of passing the center as an argument sets the center which is being used while calling setRotation on this element. setCenter only affects setRotation of this not object but not for any matrix added with createTransform. If you set the center of rotation in Inkscape (switch to rotate mode and drag the cross to the center of rotation) it is automatically loaded with setCenter so you just need to call setRotation and automatically get a rotation around the correct center. | |||
You don't need to care about tf[0] being reserved as it only reserves the index 0 and doesn't affect anything if not used. createTransform creates a new matrix with the next unused index starting at 1 (0 is reserved). If you later call setRotation directly on an element a new Transform will be created but this time using tf[0] to ensure it is applied before all other matrices and therefore rotating the object around its own center before being moved around. | |||
For the HUD I'd set the rotation center correctly inside Inkscape and later on just call ladder.setRotation to rotate for changes in the roll angle. Afterwards create a Transform and use setTranslate for changes in pitch angle. | |||
=== setTranslation === | === setTranslation === | ||