In semi-pseudocode, you want to do something like this:

render_window::on_mousedown(point)
{
	if(selmode == lasso)
		pt_array.clear();
		pt_array.push_back(point);
		set_capture(this);
}

render_window::on_mousemove(point)
{
	if(selmode == lasso)
		if(get_capture() = this))
			pt_array.push_back(point);
}

render_window::on_mouseup(point)
{
	if(selmode == lasso)
		release_capture(this);
		pt_array.push_back(point);
		build_mask(pt_array);
		pt_array.clear();
}

build_mask(pt_array)
{
	if(win32)
		set up offscreen 1-bit dib
		dib.clear(black);
		define polygon from pt_array
		make region from polygon
		dib.selectobject(region)
		dib.fillregion(white);
		povray.mask.make_from(dib); // white = transparent
		
}

povray::render_scene(...)
{
	...
	for each pixel in scene
		if(mask.exists and mask pixel is black)
			continue;
		...
		render(pixel);
}

Ray


Sven Littkowski wrote:
> Sounds very interesting, but also very ununderstandable! Ray, I just never 
> had POV-Ray doing such. I even don't know, how. Can you give me/us more 
> details? Can you describe the entire procedure?
> 
> Sorry for my unknowledgement, but I really want to understand your idea as I 
> truly look for suggestions.
> 
> Thanks, greetings,
> 
> Sven
> 
> 
> 
> 
> 
> "Ray Gardener" <ray### [at] daylongraphicscom> schrieb im Newsbeitrag 
> news:445c4cab$1@news.povray.org...
>> It's trivially easy, actually.  Just render the selection region to a 
>> 1-bit mask, then test the mask pixels to see if a display pixel should be 
>> rendered.
>>
>> Ray
>>
>>
>> Chambers wrote:
>>> Alain wrote:
>>>> Also, rendering an irregular shaped area could ultimately be slower than 
>>>> a slightly to large area. This will be due to a substentialy more 
>>>> complex code. The code for a simple square section is simple: you limit 
>>>> the region to render. That for an arbitrary free-hand capture will need 
>>>> to test every pixel against the desired area. You may also need to 
>>>> render, but not display, in a, square, region larger than the selected 
>>>> area.
>>> While I don't necessarily think we need this feature, I don't think it 
>>> would be that bad.  For each line, you could just store the beginning and 
>>> ending points (assuming only convex shapes were allowed) and render a 
>>> straight line across.
>>>
>>> ...Chambers 
> 
>

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