video_core: continue a split instance loop at its own instance index

Writing any register outside the instance loop's own methods now draws the
waiting instances first, so the batch sees the base instance it was begun
with. When a title writes another register in the middle of a loop, such
as a per-instance constant buffer, the loop is drawn in several batches,
and each later batch started again at global_base_instance_index with one
extra instance, so it used the instance IDs of the first records.

Count the instances already drawn for the current loop and start the next
batch after them, without the extra first-instance draw. A loop that is
not split is drawn exactly as before.

Follow-up to 2ad0830d2f and eb99da6072.

Assisted-by: Claude Sonnet 5.5 (implementation and commit message)

1 files changed, 2 insertions, 2 deletions

diff --git a/src/video_core/engines/maxwell_3d.cpp b/src/video_core/engines/maxwell_3d.cpp
index 9731f54584..4ef7d42979 100644
--- a/src/video_core/engines/maxwell_3d.cpp
+++ b/src/video_core/engines/maxwell_3d.cpp
@@ -342,7 +342,7 @@ void Maxwell3D::ProcessDirtyRegisters(u32 method, u32 argument) {
     // the state they were begun with: NVN's draw macros reset the base instance (and its copy in
     // c[0][0x644]) right after the loop, before the macro returns.
     if (draw_manager.HasDeferredDraw() && !DrawManager::IsInstanceLoopMethod(method)) [[unlikely]] {
-        draw_manager.DrawDeferred(*this);
+        draw_manager.DrawDeferred(*this, true);
     }
     regs.reg_array[method] = argument;
     for (auto const& table : dirty.tables)
@@ -537,7 +537,7 @@ void Maxwell3D::CallMultiMethod(Core::System& system, u32 method, const u32* bas
     }
     // As in ProcessDirtyRegisters: the paths below write without it.
     if (draw_manager.HasDeferredDraw() && !DrawManager::IsInstanceLoopMethod(method)) [[unlikely]] {
-        draw_manager.DrawDeferred(*this);
+        draw_manager.DrawDeferred(*this, true);
     }
     switch (method) {
     case MAXWELL3D_REG_INDEX(const_buffer.buffer):