On Thu, Jun 23, 2016 at 1:04 PM, Param Hanji <param.catchch...@gmail.com>
wrote:
>
>
> On Wed, Jun 22, 2016 at 7:43 PM Vasco Alexandre da Silva Costa <
> vasco.co...@gmail.com> wrote:
>
>> On Wed, Jun 22, 2016 at 2:36 PM, Param Hanji <param.catchch...@gmail.com>
>> wrote:
>>
>>> - in copy_to_cpu if gpu_seg->seg_sti is zero the cpu_seg->seg_stp->st_id
>>>> will be uninitialized. worse. you are writing to an uninitialized pointer.
>>>> what I think you want to do is lookup the seg_stp pointer based on the
>>>> seg_sti id and use that to initialize the cpu->seg_stp pointer field.
>>>>
>>>
>>> I can't find the relevant code that initializes the seg_stp. The rt_shot
>>> methods in primitive files simply copy the passed soltab pointer. In
>>> shootray(), this is obtained from a cutter, which is a union for space
>>> partitioning.
>>>
>>> My understanding is that the structure soltab keeps track of all the
>>> relevant information pertaining to a solid (primitive). On the GPU side,
>>> only ID (seg_sti) is used. How do I initialize the cpu->seg_stp field?
>>>
>>
>> One way to do it would be to store the soltab pointers in an array
>> indexed by the integer solid 'id'. You should be able to do this in
>> src/librt/primitives/primitive_util.c:clt_db_store. It's iterating through
>> a cutter's solids and the current solid pointer is stored in the variable
>> 'stp'.
>>
>> I realized I can loop through all the all the solids using the macros
> defined in soltab.h like this
>
> RT_VISIT_ALL_SOLTABS_START(stp, a->a_rt_i) {
> if (stp->st_id == (int)gpu_seg->seg_sti)
> cpu_seg->seg_stp = stp;
> } RT_VISIT_ALL_SOLTABS_END
>
> When I ran this I noticed that some of the GPU segments don't have seg_sti
> initialized (value 0). How can I process these?
>
This won't work. You see the st_id doesn't define a unique per solid
identifier. It's the solid class identifier.
So let's say you have two ellipsoids in the scene. Both solids will have an
st_id of ID_ELL. Sorry about that I induced you in error a couple of emails
back.
Also the GPU side seg_sti doesn't have the same meaning at all. It's a
unique solid id. In the soltabs list. So '0' would be the first valid solid
in the soltabs list. So your code should work like this:
unsigned int i=0;
RT_VISIT_ALL_SOLTABS_START(stp, a->a_rt_i) {
/* Ignore "dead" solids in the list. (They failed prep) */
if (stp->st_aradius <= 0) continue;
/* Infinite solids make the BVH construction explode. */
if (stp->st_aradius >= INFINITY) continue;
if (i == gpu_seg->seg_sti) {
cpu_seg->seg_stp = stp;
break;
}
i++;
} RT_VISIT_ALL_SOLTABS_END
--
Vasco Alexandre da Silva Costa
PhD in Computer Engineering (Computer Graphics)
Instituto Superior Técnico/University of Lisbon, Portugal
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