[Mesa-dev] [PATCH 00/21] Gallium: making user vertex buffers optional and other goodness

[Christoph Bumiller]

On 04/14/2012 01:45 PM, Marek Olšák wrote:
> On Sat, Apr 14, 2012 at 10:03 AM, Jose Fonseca <jfonseca at vmware.com> wrote:
>> Hi Marek,
>>
>> ----- Original Message -----
>>> Hi everyone,
>>>
>>> This series adds these optional features to st/mesa:
>>> - uploading user vertex buffers
>>> - translating unsupported vertex formats into floats
>>> - vertex data with unaligned buffer_offset, src_offset, or stride is
>>> transformed such that it's aligned
>>>
>>> These vertex formats are automatically translated into float if the
>>> driver doesn't expose them through
>>> is_format_supported(PIPE_BIND_VERTEX_BUFFER):
>>> - PIPE_FORMAT_*16_FLOAT
>>> - PIPE_FORMAT_*64_FLOAT
>>> - PIPE_FORMAT_*32_FIXED
>>> - PIPE_FORMAT_*32_UNORM
>>> - PIPE_FORMAT_*32_SNORM
>>> - PIPE_FORMAT_*32_USCALED
>>> - PIPE_FORMAT_*32_SSCALED
>>>
>>> This series doesn't deal with uploads of:
>>> - user index buffers
>>> - user constant buffers
>>>
>>> It's all done by moving the u_vbuf module out of the radeon drivers
>>> and into the Mesa state tracker. u_vbuf is installed into
>>> cso_context, where it overrides a few functions. The installation is
>>> done only when the driver doesn't support a certain feature (a
>>> vertex format or user buffers or has buffer alignment restrictions).
>>> That's pretty much it.
>>
>> I've looked at the series a bit more closely, and it looks great to me.
>>
>>> There are new CAPs for vertex buffer alignment and, of course, user
>>> vertex buffers. I had to add "uint8_t *user_ptr" into pipe_resource,
>>> so that I could access the user buffer pointer in the state tracker.
>>
>> The new CAPS talk about DWORD alignment only. What about the alignment of doubles? Does GL or any hardware allow non-aligned doubles?
> 
> To my knowledge, no hardware driver implements doubles yet. This may
> be revisited in the future. As far as GL is concerned, my recollection
> is that it allows pretty much anything.
> 

All current hardware (that I know of) fetches doubles as "raw" data
using 2 attribute slots for vec3, vec4.

Btw. I find "DWORD" too imprecise as well.

> Marek
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