[Feature requests] Screenshot resolution multiplier; rotate plane section tool

[cnr-isti-vclab]

[Feature requests] Screenshot resolution multiplier; rotate plane section tool

[mcallieri]

hi. Thanks for the feedback.

1. the screenshot functionality is something new, and we would like to expand it in the future. High-res images could be a good idea.
   There are two ways to do that:

• tiled rendering (as it is currently done in MeshLab): the scene is rendered multiple times, every time drawing only a chunk of the viewport. Chunks are collected and saved as a single image.
• offscreen buffer: a new buffer of the appropriate size is created and rendered into, and then saved.
  Neither of these can be easily implemented, at the moment, but we will think about it.
  Finally, there is the problem of multiresolution. The engine try to load and draw a representation that is "good" for the current viewpoint and resolution. We cannot increase the resolution TOO MUCH, because the model would be still displayed at a geometrical detail good for your screen. This is one of the cases where, if you need the maximum resolution, you need to work locally :)

2. good news, the slanted plane is already available. It is not on the features described in the tutorials because it does not have a pre-made interface (you have to create your own in HTML/javascript), and because the parameters are more difficult to control w.r.t. the "axis-aligned sections".
   As soon as I have a minute, I'll write down some information on how to use this feature

[mcallieri]

As I said, the oblique section does NOT have a ready-made interface, you have to create one depending on your needs.
as an example of interface, see http://vcg.isti.cnr.it/varie/terrain/M2_AUTO.html

The oblique sectioning plane is stored in the format normal + offset (and sign).
The plane at offset 0 passes through the center of the scene bounding sphere.

To control the oblique section, you have to use these functions:

resetClippingPlane();
removes the current oblique section plane. The section disappears

setClippingPlane(angle1, angle2, sign, offset)

angle1 and angle2 can be between -90 +90, and control how much tilt over Y and Z axis
sign can be 1.0 (positive side is clipped) or -1 (negative side is clipped)
offset can be between -100 100, and determines the offset % of the plane, i.e. how much the plane is far from the scene center.

if you want, you can control the offset with an absolut value. e.g. I want to move the plane 12mm, you may add another parameter with the offset
setClippingPlane(angle1, angle2, sign, 0, offsetabs)

if you know the exact plane you need, you may also specify directly the normal and offset of the plane in absolute values.
setClippingPlaneExplicit(axis, offset)
axis is a vector with three components, nx,ny,nz. the vectors has to be normalized.
offset is

To have an example, load the minimal example, open the console, and try these commands

presenter.setClippingPlane(0, 0, 1.0, 0.0)
straight vertical section (perpendicular to X), centered on the center of the scene, right half is removed

presenter.setClippingPlane(0, 0, -1.0, 0.0)
straight vertical section (perpendicular to X), centered on the center of the scene, left half is removed

presenter.setClippingPlane(45, 0, 1.0, 0.0)
vertical section, rotated 45° on the Y axis, centered on the center of the scene, front-right half is removed

presenter.setClippingPlane(0, 45, 1.0, 0.0)
vertical section, rotated 45° on the Z axis, centered on the center of the scene, top-right half is removed

presenter.setClippingPlane(0, 45, 1.0, 20.0)
vertical section, rotated 45° on the Z axis, 20% offset from the center, top-right half is removed
presenter.setClippingPlane(0, 45, 1.0, -20.0)
vertical section, rotated 45° on the Z axis, -20% offset from the center, top-right half is removed

presenter.setClippingPlane(0, 45, 1.0, 0.0, 6)
vertical section, rotated 45° on the Z axis, 6mm offset from the center, top-right half is removed
presenter.setClippingPlane(0, 45, 1.0, 0.0, -6)
vertical section, rotated 45° on the Z axis, -6mm offset from the center, top-right half is removed

[afr-git]

Thank you Marco for replying in such detail.

To convey what I was envisaging with the rotation of the plane section tool to be feature like my attached image, enabling the rotation of the existing sections in tandem with translation.