[vk] Fix fallback viewport/scissor origin handling (#294)

When viewport_scale_offset_enabled is disabled, the fallback path
previously assumed a top-left origin for both viewport and scissor.
This caused incorrect positioning or inverted geometry when the GPU
state expected a lower-left origin.

This change:
- Adjusts viewport setup: if window_origin is lower-left, shift Y and
  flip height negative to emulate lower-left in Vulkan’s top-left space.
- Updates scissor setup: recalculates Y for lower-left origin and
  ensures width/height fall back to 1 if zero, avoiding invalid extents.

This aligns Vulkan’s viewport/scissor behavior with Maxwell state,
fixing rendering issues in paths without scale/offset enabled.

Co-authored-by: MaranBr <maranbr@outlook.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/294
Co-authored-by: Shinmegumi <shinmegumi@eden-emu.dev>
Co-committed-by: Shinmegumi <shinmegumi@eden-emu.dev>

0 files changed, 0 insertions, 0 deletions