Objects with alpha maps cast wrong ray shadows in BI #48818

New Issue

Alex · 2016-07-09T08:57:51+02:00

Alex commented

2016-07-09 08:57:51 +02:00

System Information
Intel Core i7, 8 Gb RAM, AMD Radeon HD 7700
Windows 7 x64

Blender Version
Broken: 2.77 1b45c52
Worked: 2.77a abf6f08

Short description of error
Tested 1b45c52 and while general problem with shadow placement seems to be solved, the next issue with upside-down shadows is still there.
Edit: I've made additional tests and found out that this problem is a lot bigger - it is reproducible with any object and any alpha map so this is not specific to particles. I have tried .png files and simple grayscale bitmaps with "RGB to Intensity" option and both seems to behave the same.

Exact steps for others to reproduce the error
You can use my test file - just open it and hit render.
Particle_object_artifacts1.blend

You can also recreate it yourself using a following setup:

Open Blender, add a simple Plane with UVs and assign a particle system to it.
Set start and end frames to 1 and particle number to 10 so each one could cast a definite shadow.
Switch particle type to Billboard and scale them to 10 so each billboard will be clearly visible. It is also possible to use custom objects as well.
Apply base material and turn on "Receive Transparent" option. Add material and texture with alpha map and make particles use that material.
Set any lamp that can cast ray shadows.
Render your scene.

The most simple case can be set like this:

Open Blender, create two simple planes with UVs.
Rotate one of the planes 90 degrees so it will cast shadow on another plane.
Apply material to horizontal plane and turn on "Receive Transparent" option.
Apply material to vertical plane and set any kind of alpha map to it. You can use .png file with alpha or simple grayscale bitmap.
Render your scene.

In 2.77a shadows will be placed as expected
In latest 2.77 shadows will be turned upside-down. Notice that in my example text is flipped in addition to being upside-down
Image Mapping -> Repeat and Checker produce upside-down shadow. Using Crop Minimum/Maximum produce wrong shadow
Image Mapping -> Clip and Clip Cube produce no shadow
Image Mapping -> Extend produce wrong shadow

**System Information** Intel Core i7, 8 Gb RAM, AMD Radeon HD 7700 Windows 7 x64 **Blender Version** Broken: 2.77 1b45c52 Worked: 2.77a abf6f08 **Short description of error** Tested 1b45c52 and while general problem with shadow placement seems to be solved, the next issue with upside-down shadows is still there. **Edit:** I've made additional tests and found out that this problem is a lot bigger - it is reproducible with any object and any alpha map so this is not specific to particles. I have tried .png files and simple grayscale bitmaps with "RGB to Intensity" option and both seems to behave the same. **Exact steps for others to reproduce the error** You can use my test file - just open it and hit render. [Particle_object_artifacts1.blend](https://archive.blender.org/developer/F320550/Particle_object_artifacts1.blend) ![Upsidedown_shadows.png](https://archive.blender.org/developer/F320548/Upsidedown_shadows.png) You can also recreate it yourself using a following setup: 1. Open Blender, add a simple Plane with UVs and assign a particle system to it. 2. Set start and end frames to 1 and particle number to 10 so each one could cast a definite shadow. 3. Switch particle type to Billboard and scale them to 10 so each billboard will be clearly visible. It is also possible to use custom objects as well. 4. Apply base material and turn on "Receive Transparent" option. Add material and texture with alpha map and make particles use that material. 5. Set any lamp that can cast ray shadows. 6. Render your scene. The most simple case can be set like this: 1. Open Blender, create two simple planes with UVs. 2. Rotate one of the planes 90 degrees so it will cast shadow on another plane. 3. Apply material to horizontal plane and turn on "Receive Transparent" option. 4. Apply material to vertical plane and set any kind of alpha map to it. You can use .png file with alpha or simple grayscale bitmap. 5. Render your scene. - In 2.77a shadows will be placed as expected - In latest 2.77 shadows will be turned upside-down. Notice that in my example text is flipped in addition to being upside-down - Image Mapping -> Repeat and Checker produce upside-down shadow. Using Crop Minimum/Maximum produce wrong shadow - Image Mapping -> Clip and Clip Cube produce no shadow - Image Mapping -> Extend produce wrong shadow

Alex commented

2016-07-09 08:57:51 +02:00

Changed status to: 'Open'

Alex commented

2016-07-09 08:57:51 +02:00

Added subscriber: @SpectreFirst

Alex changed title from ~~Particles with transparency texture cast upside-down shadows in BI~~ to Objects with alpha maps cast wrong ray shadows in BI

2016-07-09 11:34:24 +02:00

blender-admin commented

2016-07-12 15:40:40 +02:00

This issue was referenced by 51b274a6be

This issue was referenced by 51b274a6be5d59c7009fd3f439821d1e15b72709

Sergey Sharybin commented

2016-07-12 15:41:00 +02:00

Changed status from 'Open' to: 'Resolved'

Sergey Sharybin closed this issue

2016-07-12 15:41:00 +02:00

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Objects with alpha maps cast wrong ray shadows in BI #48818