Move a Parallel Camera

Jim

I have this snippet to zoom out - just moves the camera away from the taget along the line-of-sight. Any idea why it works when the Camera is Perspective, but not Parallel?


factor = 0.5
model = Sketchup.active_model
view = model.active_view
c = view.camera
t = c.target
e = c.eye
up = c.up
vec = t - e
vec.length = vec.length * factor
c.set(e-vec, t, up)

Chris Fullmer

I changed the factor to 1000 and ran it about 10 times really fast.....that broke my SketchUp

I have not got the right answer, but in parallel mode, backing the camera out should not widen the view of what is ont he screen. It seems like you would need to widen the FOV or something to make it feel like you are backing up.

Jim

Thanks Chris, that makes sense.

When I plot the Camera eye over several "zoom outs", the cpoints do indicate the Camera is moving away.

So I'm still not sure why the view doesn't appear to move, even if the Camera is. Zoom and Pan still work with a Parallel Camera. Moving the Camera away should still make everything appear smaller.

mitcorb

I don't really know what I'm talking about, but from an intuitive view, do you have to transform the OpenGL frustum or camera cone of vision in order for the display to "shrink"? Or is the frustum a fixed thing and ...mumble...mumble??

Dan Rathbun

Does appending a call to view.refresh (at the end of the code,) have any effect ??

Jim

No, no difference.

I did notice that when I switch back to a Perspective Camera, the camera jumps way back.

Dan Rathbun

OK.. and what happens when you switch back to Parallel ?

Dan Rathbun

A few other questions:

Do these have any effect?

view.invalidate()

view.dynamic=true

Jim

Neither has nay effect.

Chris Fullmer

Maybe change to perspective mode, then move, then jump back to parallel? Or do that on a camera that is not active_view and then apply that camera to the active view?

Jim

Yep, thanks. I can make something work. I guess at this point I am curious to understand what's going on.

Dan Rathbun

@chris fullmer said:

Maybe change to perspective mode, then move, then jump back to parallel?

That is what I meant when I asked:
@dan rathbun said:

OK.. and what happens when you switch back to Parallel ?

Dan Rathbun

Solved.

This code works no matter what mode the camera is in, AND resets the mode back to the previous mode. (See ### bracketed statements that I added.)

zoomtest.rb

<span class="syntaxdefault"></span><span class="syntaxcomment">#<br /><br /></span><span class="syntaxdefault">module SU_Test<br /><br />  </span><span class="syntaxcomment">#<br /><br /></span><span class="syntaxdefault">  def self</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">zoomtest</span><span class="syntaxkeyword">()<br /></span><span class="syntaxdefault">    factor </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> 0.5<br />    model </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> Sketchup</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_model<br />    view </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> model</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">active_view<br />    c </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> view</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">camera<br />    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">    cp</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">perspective</span><span class="syntaxkeyword">?<br /></span><span class="syntaxdefault">    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">    t </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">target<br />    e </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">eye<br />    up </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">up<br />    vec </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> t </span><span class="syntaxkeyword">-</span><span class="syntaxdefault"> e<br />    vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> vec</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">length </span><span class="syntaxkeyword">*</span><span class="syntaxdefault"> factor<br />    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">    c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">perspective</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">true if cp</span><span class="syntaxkeyword">==</span><span class="syntaxdefault">false<br />    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">    c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">set</span><span class="syntaxkeyword">(</span><span class="syntaxdefault">e</span><span class="syntaxkeyword">-</span><span class="syntaxdefault">vec</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> t</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> up</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">    c</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">perspective</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">false if cp</span><span class="syntaxkeyword">==</span><span class="syntaxdefault">false<br />    </span><span class="syntaxcomment">###<br /></span><span class="syntaxdefault">  end<br /><br />  unless defined</span><span class="syntaxkeyword">?(@</span><span class="syntaxdefault">LoadedOnce</span><span class="syntaxkeyword">)==</span><span class="syntaxstring">'instance-variable'<br /></span><span class="syntaxdefault">    </span><span class="syntaxkeyword">@</span><span class="syntaxdefault">LoadedOnce</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">false<br />  end<br /><br />  def self</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">loaded_once</span><span class="syntaxkeyword">()<br /></span><span class="syntaxdefault">    </span><span class="syntaxkeyword">@</span><span class="syntaxdefault">LoadedOnce<br />  end<br />  <br />  def self</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">loaded_once</span><span class="syntaxkeyword">=(</span><span class="syntaxdefault">arg</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">    </span><span class="syntaxkeyword">@</span><span class="syntaxdefault">LoadedOnce</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">arg<br />  end<br /><br />end </span><span class="syntaxcomment"># module<br /><br /></span><span class="syntaxdefault">  unless SU_Test</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">loaded_once</span><span class="syntaxkeyword">()<br /></span><span class="syntaxdefault">    </span><span class="syntaxcomment">#<br /></span><span class="syntaxdefault">    UI</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">menu</span><span class="syntaxkeyword">(</span><span class="syntaxstring">'Plugins'</span><span class="syntaxkeyword">).</span><span class="syntaxdefault">add_item</span><span class="syntaxkeyword">(</span><span class="syntaxstring">'Zoom Out Test'</span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">{</span><span class="syntaxdefault"> SU_Test</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">zoomtest</span><span class="syntaxkeyword">()</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">}<br /></span><span class="syntaxdefault">    </span><span class="syntaxcomment">#<br /></span><span class="syntaxdefault">    SU_Test</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">loaded_once</span><span class="syntaxkeyword">=</span><span class="syntaxdefault">true<br />    </span><span class="syntaxcomment">#<br /></span><span class="syntaxdefault">  end<br /></span>

jhauswirth

You need to use camera.height in parallel mode.

Jim

@jhauswirth said:

You need to use camera.height in parallel mode.

Thank you, that works.