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Emulator Issues #13862

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Broken Shadows in "Hot Wheel: Velocity X"

Emulator Issues #13862: Broken Shadows in "Hot Wheel: Velocity X"

Added by flacs 7 months ago. Updated 7 months ago.

Status:
Accepted
Priority:
Normal
Assignee:
-
% Done:

0%

Operating system:
N/A
Issue type:
Bug
Milestone:
Regression:
No
Relates to usability:
No
Relates to performance:
No
Easy:
No
Relates to maintainability:
No
Regression start:
Fixed in:

Description

Game Name?

Hot Wheels: Velocity X

Game ID? (right click the game in the game list, Properties, Info tab)

GHWE78

MD5 Hash? (right click the game in the game list, Properties, Verify tab, Verify Integrity button)

819f06787ec1ca0a9b8608215abb7270

What's the problem? Describe what went wrong.

The second shadow volume pass is using blending with destination factor 1-src_color to implement a decrement. In the software renderer this works out. In all other backends the second pass does not modify the frame buffer.

What steps will reproduce the problem?

Drive the car in circles to cast a shadow to the side. Notice that the shadow looks physically incorrect.

Is the issue present in the latest development version? For future reference, please also write down the version number of the latest development version.

Yes, 2506-340.

Is the issue present in the latest release? For future reference, please also write down the version number of the latest release.

Yes, 2506a.

Is there anything else that can help developers narrow down the issue? (e.g. logs, screenshots,
configuration files, savefiles, savestates)

These are the correct shadow pass results of the software renderer (alpha channel, value scaled for visibility).

Increment:
correct EFB alpha after 1. shadow pass (increment)

Decrement:
correct EFB alpha after 2. shadow pass (decrement)


Files

hotwheels.zip (1.81 MB) hotwheels.zip fifo log flacs, 08/09/2025 06:26 AM
step1.png (3.51 KB) step1.png correct EFB alpha after 1. shadow pass (increment) flacs, 08/09/2025 06:27 AM
step2.png (3.42 KB) step2.png correct EFB alpha after 2. shadow pass (decrement) flacs, 08/09/2025 06:27 AM

Updated by flacs 7 months ago Actions #1

A workaround that modifies the blending mode is documented on the wiki: https://wiki.dolphin-emu.org/index.php?title=Hot_Wheels_Velocity_X#Somewhat_Broken_Shadows

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