Assigning different materials to different parts of a Mesh cause them to be transparent. #70466

New Issue

Zino Guerr · 2019-10-03T00:30:36+02:00

Zino Guerr commented

2019-10-03 00:30:36 +02:00

System Information
Operating system: Windows-10-10.0.1709 64 Bits
Graphics card: GeForce GTX 1050 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.30

Blender Version
Broken: version: 2.81 (sub 13), branch: master, commit date: 2019-10-02 17:42, hash: aabd8701e9
Worked: (optional)

Short description of error
If i assign materials to different Faces of a single Mesh they become transparent and switching slots order or pushing anyone up makes it transparent.

Exact steps for others to reproduce the error
Assign different Materials to Suzanne second one becomes transparent.
Switching the order will switch the one who becomes transparent and the more you add the whole Mesh gets affected.

[Based on the default startup or an attached .blend file (as simple as possible)]
Mat.blend

**System Information** Operating system: Windows-10-10.0.1709 64 Bits Graphics card: GeForce GTX 1050 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.30 **Blender Version** Broken: version: 2.81 (sub 13), branch: master, commit date: 2019-10-02 17:42, hash: `aabd8701e9` Worked: (optional) **Short description of error** If i assign materials to different Faces of a single Mesh they become transparent and switching slots order or pushing anyone up makes it transparent. **Exact steps for others to reproduce the error** Assign different Materials to Suzanne second one becomes transparent. Switching the order will switch the one who becomes transparent and the more you add the whole Mesh gets affected. ![mat.png](https://archive.blender.org/developer/F7786533/mat.png) [Based on the default startup or an attached .blend file (as simple as possible)] [Mat.blend](https://archive.blender.org/developer/F7786530/Mat.blend)

Zino Guerr commented

2019-10-03 00:30:36 +02:00

Added subscriber: @Znio.G

blender-admin commented

2019-10-03 00:30:36 +02:00

#78224 was marked as duplicate of this issue

blender-admin commented

2019-10-03 00:30:36 +02:00

#70492 was marked as duplicate of this issue

blender-admin commented

2019-10-03 00:30:36 +02:00

#70472 was marked as duplicate of this issue

blender-admin commented

2019-10-03 00:30:36 +02:00

#70477 was marked as duplicate of this issue

blender-admin commented

2019-10-03 00:30:36 +02:00

#70469 was marked as duplicate of this issue

Clément Foucault was assigned by Brecht Van Lommel

2019-10-03 03:07:53 +02:00

Brecht Van Lommel commented

2019-10-03 03:08:04 +02:00

Added subscriber: @rimpotche

Daniel Santana commented

2019-10-03 12:28:16 +02:00

Added subscriber: @dgsantana

Daniel Santana commented

2019-10-03 12:31:25 +02:00

Just another example on the latest nVidia driver (GeForce RTX 2080 SUPER, 4.5.0 NVIDIA 436.48)

Just another example on the latest nVidia driver (GeForce RTX 2080 SUPER, 4.5.0 NVIDIA 436.48) ![image.png](https://archive.blender.org/developer/F7787278/image.png)

Brecht Van Lommel commented

2019-10-03 12:41:34 +02:00

Added subscriber: @JulienKaspar

Daniel Santana commented

2019-10-03 13:41:21 +02:00

Another test.

Fig 1. Missing "grass" material

Switching the order of the materials

Fig 2. Missing polys but both materials appear

Another test. ![image.png](https://archive.blender.org/developer/F7787326/image.png) Fig 1. Missing "grass" material Switching the order of the materials ![image.png](https://archive.blender.org/developer/F7787329/image.png) Fig 2. Missing polys but both materials appear

Brecht Van Lommel commented

2019-10-03 13:46:56 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2019-10-03 13:46:56 +02:00

I'm looking into this. It seems that if there are N faces with the first material, then the first N faces with the second material get hidden.

Brecht Van Lommel commented

2019-10-03 14:04:11 +02:00

The result returned by elem_offset() in gpu_batch.c seems to be double what it needs to be.

This makes things work:

diff --git a/source/blender/gpu/intern/gpu_batch.c b/source/blender/gpu/intern/gpu_batch.c
index c08680d..23f7780 100644
--- a/source/blender/gpu/intern/gpu_batch.c
+++ b/source/blender/gpu/intern/gpu_batch.c
@@ -670,7 +670,7 @@ void GPU_batch_draw_advanced(GPUBatch *batch, int v_first, int v_count, int i_fi
     const GPUIndexBuf *el = batch->elem;
     GLenum index_type = INDEX_TYPE(el);
     GLint base_index = BASE_INDEX(el);
-    void *v_first_ofs = elem_offset(el, v_first);
+    void *v_first_ofs = (void *)((int)elem_offset(el, v_first) / 2);
 
     if (GPU_arb_base_instance_is_supported()) {
       glDrawElementsInstancedBaseVertexBaseInstance(

The result returned by `elem_offset()` in `gpu_batch.c` seems to be double what it needs to be. This makes things work: ``` diff --git a/source/blender/gpu/intern/gpu_batch.c b/source/blender/gpu/intern/gpu_batch.c index c08680d..23f7780 100644 --- a/source/blender/gpu/intern/gpu_batch.c +++ b/source/blender/gpu/intern/gpu_batch.c @@ -670,7 +670,7 @@ void GPU_batch_draw_advanced(GPUBatch *batch, int v_first, int v_count, int i_fi const GPUIndexBuf *el = batch->elem; GLenum index_type = INDEX_TYPE(el); GLint base_index = BASE_INDEX(el); - void *v_first_ofs = elem_offset(el, v_first); + void *v_first_ofs = (void *)((int)elem_offset(el, v_first) / 2); if (GPU_arb_base_instance_is_supported()) { glDrawElementsInstancedBaseVertexBaseInstance( ```

Ovionis commented

2019-10-03 14:11:24 +02:00

Added subscriber: @Phigon

Clément Foucault commented

2019-10-03 14:18:03 +02:00

Changed status from 'Open' to: 'Resolved'

Clément Foucault closed this issue

2019-10-03 14:18:03 +02:00

Tyler commented

2019-10-03 14:18:34 +02:00

Added subscriber: @Tyler-Foo

blender-admin commented

2019-10-03 14:43:31 +02:00

This issue was referenced by 11768d1c9f

This issue was referenced by 11768d1c9f4374ffa512a0d90cfde776d3e9babe

Brecht Van Lommel commented

2019-10-03 16:17:05 +02:00

Added subscribers: @starnokia9310, @alausic, @WybrenvanKeulen

Brecht Van Lommel commented

2019-10-03 22:57:24 +02:00

Added subscriber: @YanDaik

cadtofu commented

2019-12-09 08:48:42 +01:00

Added subscriber: @cadtofu

cadtofu commented

2019-12-09 08:48:42 +01:00

same problem happend to me.
blender 2.81/2.81a win64 (both official release)
nvidia card driver version, both v341.74 and v342.01
affect eevee/workbench engine, not affect cycles engine.

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce 310M/PCIe/SSE2 NVIDIA Corporation 3.3.0

same problem happend to me. blender 2.81/2.81a win64 (both official release) nvidia card driver version, both v341.74 and v342.01 affect eevee/workbench engine, not affect cycles engine. **System Information** Operating system: Windows-10-10.0.17763 64 Bits Graphics card: GeForce 310M/PCIe/SSE2 NVIDIA Corporation 3.3.0

Richard Antalik commented

2020-06-25 14:24:28 +02:00

Added subscribers: @BhaveshVishwakarma, @iss

Thomas Dinges added this to the 2.81 milestone 2023-02-08 16:46:56 +01:00

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Assigning different materials to different parts of a Mesh cause them to be transparent. #70466