[Visualpython-users] Opacity problem

[CL <clc...@gm...>]

About the opacity problem (crash when changing from opacity 1.0 to
lower), it looks like it is a bug in frame.cpp

void frame::gl_render( const view& v)

....

for (child_iterator i = children.begin(); i !=
child_iterator(children.end()); ++i) {
	if (i->translucent()) {
		// See display_kernel::draw().
		trans_children.push_back( *i.base());
		i = children.erase(i.base());
		continue;
	}

	i->outer_render(local);
}

The code is trying to move a renderable from a list to another list
when the opacity of the renderable is changing from 1.0 to something
else. But children.erase() function returns the pointer after
deletion, not the pointer before deletion.

Following similar logic in display_kernel::draw, replace the code with :

child_iterator i(children.begin());
child_iterator i_end(children.end());
while (i != i_end) {
	if (i->translucent()) {
		// See display_kernel::draw().
		trans_children.push_back( *i.base());
		i = children.erase(i.base());
		continue;
	}
	i->outer_render(local);
	i++;

It seems working on my simple test cases.


>Don't I wish it were that simple. No, objects are created with
>opacity=1.0 by default. That's why a scene contains opaque objects if
>you don't explicitly set the opacity to something different.

>b = box()
>print b.opacity # shows 1.0

>Bruce Sherwood