[PATCH] wined3d: Invalidate INDEXBUFFER device state when contents of bound index buffer is changed.

[Józef Kucia]

On Fri, Oct 28, 2016 at 3:55 PM, Henri Verbeet <hverbeet at gmail.com> wrote:
> On 28 October 2016 at 12:20, Józef Kucia <jkucia at codeweavers.com> wrote:
>> +    if (buffer->resource.bind_count)
>> +    {
>> +        if (buffer->buffer_type_hint == GL_ELEMENT_ARRAY_BUFFER)
>> +            device_invalidate_state(buffer->resource.device, STATE_INDEXBUFFER);
>> +    }
> You can merge those if-conditions.
>
> What happens exactly that makes this required?

The bound index buffer is unloaded and the game crashes on the next
draw call because we use indexed drawing with zeroish offset and
GL_ELEMENT_ARRAY_BUFFER_BINDING is 0. I've sent another patch which
targets this issue.

The other thing is that, in theory, when a buffer is modified in the
current context we should should invalidate buffer bindings for this
buffer in other contexts in order to make the contents changes visible
in other contexts. That's the reason why I was trying to restore
device_invalidate_state() call in wined3d_buffer_load(). This would
fix the regression as well. The quote from GL spec:
"If the contents of an object T are changed in a context other than the cur-
rent context, T must be attached or re-attached to at least one
binding point in the
current context, or at least one attachment point of a currently bound container
object C, in order to guarantee that the new contents of T are visible
in the current
context."