Maniphest T54554

bpy.ops.paint.image_paint with a texture requires initialization with manual paint stroke otherwise color not quite right
Confirmed, NormalKNOWN ISSUE
Actions

Assigned To
None
Authored By
Rob Hughes (RevDr)
Apr 9 2018, 4:47 PM
Tags
  • BF Blender
  • Sculpt, Paint & Texture
  • Python API
Subscribers
Philipp Oeser (lichtwerk)
Rob Hughes (RevDr)

Description

System Information
Win 10 5820K GTX 970

Blender Version
2.79b and latest daily build

Short description of error
bpy.ops.paint.image_paint with slightly wrong colors when painting on object with texture on brush before a manual paint stroke applied

Exact steps for others to reproduce the error

  1. Load attached file
  2. Run script
  3. With mouse over the cube - press space and type Simple Modal Operator to activate modal paint operator
  4. move mouse about to paint.
  5. left click to stop modal paint operator
  6. now paint on the cube normally by holding mouse button down
  7. you will see this is a slightly different color
  8. press space and type Simple Modal Operator to activate modal paint operator again
  9. move mouse around
  10. you should now see modal operator painting correctly

This seems to happen each time I change the texture on the brush to a new one (with obviously different colors on it)

Image is attached showing this.

Possibly something not being initialized properly?

Thanks you in advance for any work on this.

modal_paint.blend512 KBDownload

Related Objects

Event Timeline

Rob Hughes (RevDr) created this task.Apr 9 2018, 4:47 PM
Rob Hughes (RevDr) added a comment.Apr 9 2018, 8:57 PM

I have done a little further investigation.

It seems what is happening is this: bpy.ops.paint.image_paint does not use color space of the brush texture until after a stroke has been 'manually' done. Therefore the texture is being used as if it is in the raw texture space until a manual stroke overides this.

Rob Hughes (RevDr) added a comment.Apr 9 2018, 9:58 PM

Having looked at the code it appears that the color space initialization for the texture is done in
paint_stroke.c
function: paint_brush_update (particualy lines 239->261)

However this is never called from the python code image_paint function.

As a workaround I tried adding the following (adapted from paint_brush update function) lines of code to
function: paint_stroke_new




     if (!stroke->brush_init) {
		ups->do_linear_conversion = false;
		ups->colorspace = NULL;

		/* check here if color sampling the main brush should do color conversion. This is done here
		* to avoid locking up to get the image buffer during sampling */
		if (br->mtex.tex && br->mtex.tex->type == TEX_IMAGE && br->mtex.tex->ima) {
			ImBuf *tex_ibuf = BKE_image_pool_acquire_ibuf(br->mtex.tex->ima, &br->mtex.tex->iuser, NULL);
			if (tex_ibuf && tex_ibuf->rect_float == NULL) {
				ups->do_linear_conversion = true;
				ups->colorspace = tex_ibuf->rect_colorspace;
			}
			BKE_image_pool_release_ibuf(br->mtex.tex->ima, tex_ibuf, NULL);
		}

		stroke->brush_init = true;
	}



Which seems to fix the problem - however - I have no idea if there are serious knock on consequences to this change which would break things (is stroke->brush_init needed here?)



I am sure there is a much more elegant solution.
Philipp Oeser (lichtwerk) lowered the priority of this task from 90 to 50.Apr 12 2018, 3:06 PM
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).
Hi @Rob Hughes (RevDr) and thx for the report, 

as a first note: I can confirm the issue and also that your code fixes it (I tested without stroke->brush_init -- but needs more research...)
Sam Van Hulle (sam_vh) mentioned this in T68926: Color Management Improvements.Sep 5 2019, 12:48 PM
Dalai Felinto (dfelinto) added a project: Tracker Curfew.Dec 23 2019, 4:36 PM
Richard Antalik (ISS) edited projects, added Sculpt, Paint & Texture, Add-ons (BF-Blender); removed Tracker Curfew.Feb 10 2020, 6:35 PM
Richard Antalik (ISS) changed the subtype of this task from "Report" to "Known Issue".
Campbell Barton (campbellbarton) edited projects, added Python API; removed Add-ons (BF-Blender).Jun 19 2020, 10:42 AM
Campbell Barton (campbellbarton) moved this task from Backlog to Known Issues on the Python API board.Jun 19 2020, 11:07 AM
Julien Kaspar (JulienKaspar) moved this task from Backlog to Known Issues on the Sculpt, Paint & Texture board.Apr 20 2021, 1:10 PM