Gawain: remove limit where drawing zero items fails
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Authored by Campbell Barton (campbellbarton) on Apr 11 2017, 3:08 AM.

Details

Reviewers

Mike Erwin (merwin)
Dalai Felinto (dfelinto)

Summary

Currently immBegin & immEnd fails drawing zero elements.

I don't think this is a reasonable limitation:

it means you need to remember to check for corner cases (which migh not be found between releases).
it may complicate code to have to check for the unlikely case where nothing is drawn (which might not be obvious ahead of time).
these cases are harmless NOP's, gawain can safely do nothing, keeping things simple for the caller.

Diff Detail

Repository

rB Blender

Branch

TEMP-gawain

Build Status

Buildable 538
Build 538: arc lint + arc unit

Event Timeline

Campbell Barton (campbellbarton) created this revision.Apr 11 2017, 3:08 AM

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 11 2017, 3:13 AM

Campbell Barton (campbellbarton) added a reviewer: Dalai Felinto (dfelinto).

Campbell Barton (campbellbarton) retitled this revision from Remove limit where drawing zero items fails to Gawain: remove limit where drawing zero items fails.

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)

Campbell Barton (campbellbarton) edited the summary of this revision. (Show Details)Apr 11 2017, 3:18 AM

Note that you can draw 0 vertices with

immBeginAtMost(PRIM_X, some_nonzero_count);
/* don't call immVertex */
immEnd();

This does all the setup, skips the draw, then does all the teardown. I prefer skipping all of this when vertex count is known to be 0. It avoids useless setup/teardown & means we don't have to handle as many special cases inside Gawain. The caller is responsible for passing in meaningful values.

In the example case I would move the zero check to the very first line of drawSelectedVertices.

Revision Contents
Changeset List

Path

Size

intern/

gawain/

src/

immediate.c

8 lines

source/

blender/

editors/

space_view3d/

drawobject.c

2 lines

Diff 8596

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intern/gawain/src/immediate.c