Fix garbage frame flash on cinematic camera cuts (#720)

* Fix garbage frame flash on cinematic camera cuts

Frame interpolation blended matrices across instant camera teleports in
attract/demo and post-race cameras, flashing 1-2 frames of sheared
geometry. Complete the existing camera-epoch mechanism: flag a cut in
func_80019890 when the camera moves >100 units, and have the
interpolator snap that frame to the new view instead of blending.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Retrigger CI (transient 502 downloading libogg from gitlab.xiph.org)

* Name the cinematic shot dispatcher

Review feedback on #720: func_80019890 -> camera_start_cinematic_shot.
It starts whichever shot D_80164680 has selected for a camera, dispatching
to the per-shot setup that teleports the camera to the shot's opening
position, which is why the cut detection lives there.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Apply fix to freecam

Added FrameInterpolation_DontInterpolateCamera calls to improve camera behavior when changing target players.

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: MegaMech <MegaMech@users.noreply.github.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/enhancements/freecam/freecam.cpp b/src/enhancements/freecam/freecam.cpp
index c5ee60319..07d0f6e51 100644
--- a/src/enhancements/freecam/freecam.cpp
+++ b/src/enhancements/freecam/freecam.cpp
@@ -236,9 +236,11 @@ void freecam_keyboard_manager(Camera* camera, Vec3f forwardVector) {
     if (bFreecamUseController) {
         if (fController.buttonDepressed & R_TRIG) {
             fTargetPlayer = true;
+            FrameInterpolation_DontInterpolateCamera();
         }
         if (fController.buttonDepressed & L_TRIG) {
             fTargetPlayer = false;
+            FrameInterpolation_DontInterpolateCamera();
         }
         if (fController.buttonPressed & L_JPAD) {
             TargetPreviousPlayer = true;
@@ -273,6 +275,7 @@ void freecam_keyboard_manager(Camera* camera, Vec3f forwardVector) {
     else if (wnd->GetWindowBackend() == Ship::WindowBackend::FAST3D_DXGI_DX11) {
         if (FreecamKeyDown('F')) {
             fTargetPlayer = !fTargetPlayer;
+            FrameInterpolation_DontInterpolateCamera();
         }
         if (FreecamKeyDown('N')) {
             TargetPreviousPlayer = true;
@@ -309,6 +312,7 @@ void freecam_keyboard_manager(Camera* camera, Vec3f forwardVector) {
         const uint8_t* keystate = SDL_GetKeyboardState(NULL);
         if (FreecamKeyDown(SDL_SCANCODE_F)) {
             fTargetPlayer = !fTargetPlayer;
+            FrameInterpolation_DontInterpolateCamera();
         }
         if (FreecamKeyDown(SDL_SCANCODE_N)) {
             TargetPreviousPlayer = true;
@@ -345,6 +349,7 @@ void freecam_keyboard_manager(Camera* camera, Vec3f forwardVector) {
             fRankIndex--;
             camera->playerId = fRankIndex;
             gScreenOneCtx->player = &gPlayers[fRankIndex];
+            FrameInterpolation_DontInterpolateCamera();
         }
     }
 
@@ -354,6 +359,7 @@ void freecam_keyboard_manager(Camera* camera, Vec3f forwardVector) {
             fRankIndex++;
             camera->playerId = fRankIndex;
             gScreenOneCtx->player = &gPlayers[fRankIndex];
+            FrameInterpolation_DontInterpolateCamera();
         }
     }