LibSoftGPU: Prevent fog from overwriting the alpha channel

Fog only affects the RGB channels according to the spec.
orospakr · Dec 30, 2021 · 9d90bab · 9d90bab
1 parent f2d8fcb
commit 9d90bab
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/Userland/Libraries/LibSoftGPU/Device.cpp b/Userland/Libraries/LibSoftGPU/Device.cpp
@@ -742,8 +742,10 @@ void Device::submit_triangle(const Triangle& triangle, Vector<size_t> const& ena
  break;
  }
 
- // Mix texel with fog
- fragment = mix(m_options.fog_color, fragment, factor);
+ // Mix texel's RGB with fog's RBG - leave alpha alone
+ fragment.set_x(mix(m_options.fog_color.x(), fragment.x(), factor));
+ fragment.set_y(mix(m_options.fog_color.y(), fragment.y(), factor));
+ fragment.set_z(mix(m_options.fog_color.z(), fragment.z(), factor));
  }
 
  return fragment;