Skip drawing invisible voxel sections

CREDITS.md

@@ -52,6 +52,7 @@ This page lists all the individual contributions to the project by their author.
   - MP saves support for quicksave command and savegame trigger action
   - Ported XNA CnCNet Client MP save handling
   - Retint fix toggle
+  - Voxel drawing invisible sections skip
 - **Uranusian (Thrifinesma)**:
   - Mind Control enhancement
   - Custom warhead splash list
@@ -546,6 +547,7 @@ This page lists all the individual contributions to the project by their author.
   - Fix a jumpjet crash related to voxel shadow drawing
   - Replace `BLOWFISH.DLL` using Red Alert source code
   - Adjust the dehardcoding of the 255 `OverlayType` limit to a different format
+  - Voxel drawing invisible sections skip
 - **CrimRecya**:
   - Fix `LimboKill` not working reliably
   - Allow using waypoints, area guard and attack move with aircraft

docs/Fixed-or-Improved-Logics.md

@@ -307,6 +307,7 @@ This page describes all ingame logics that are fixed or improved in Phobos witho
 - Fixed the bug that `DeploysInto` and `UndeploysInto` will make damaged techno lose 1 health.
 - Fixed the issue that the Jumpjet must end its movement before starting the next mission.
 - Fixed an issue where parachute units would die upon landing if bridges were destroyed during their descent.
+- Voxel drawing code now skips sections that are invisible (have all zeros in the transform matrix main diagonal, meaning that the scale is 0% on all axes), thus increasing drawing performance for some voxels.
 
 ## Fixes / interactions with other extensions
 

docs/Whats-New.md

@@ -610,6 +610,7 @@ Vanilla fixes:
 - Fixed the bug that `DeploysInto` and `UndeploysInto` will make damaged techno lose 1 health (by CrimRecya)
 - Fixed the issue that the Jumpjet must end its movement before starting the next mission (by TaranDahl)
 - Fixed an issue where parachute units would die upon landing if bridges were destroyed during their descent (by FlyStar)
+- Voxel drawing code now skips sections that are invisible (have all zeros in the transform matrix main diagonal, meaning that the scale is 0% on all axes), thus increasing drawing performance for some voxels (by Kerbiter, ZivDero)
 
 Phobos fixes:
 - Fixed the bug that `AllowAirstrike=no` cannot completely prevent air strikes from being launched against it (by NetsuNegi)

src/Misc/Hooks.BugFixes.cpp

@@ -2,6 +2,7 @@
 #include <EventClass.h>
 #include <JumpjetLocomotionClass.h>
 #include <TunnelLocomotionClass.h>
+#include <FileFormats/HVA.h>
 
 #include <Ext/BuildingType/Body.h>
 #include <Ext/Techno/Body.h>
@@ -3164,3 +3165,27 @@ DEFINE_HOOK(0x7442AB, UnitClass_ReadyToNextMission_FallingDown, 0x6)
 	GET(FootClass*, pThis, ESI);
 	return pThis->IsFallingDown ? ReturnZero : 0;
 }
+
+// sadly, useful for uncached voxels specifically, but no reason for the code to go to waste
+DEFINE_HOOK(0x706F64, TechnoClass_RenderVoxelObject_SkipInvisibleSections, 0x0)
+{
+	enum { SkipLayer = 0x706FDF };
+
+	GET(MotLib* const, pMotLib, EDI);
+
+	// stolen code
+	if (!pMotLib)
+		return 0x706FBD;
+
+	GET(int const, layer, EBX);
+	GET_STACK(unsigned int const, frame, STACK_OFFSET(0x13C, 0x18));
+
+	auto mtx = pMotLib->GetLayerMatrix(layer, frame);
+
+	if (mtx.row[0][0] == 0.0 && mtx.row[1][1] == 0.0 && mtx.row[2][2] == 0.0)
+		return SkipLayer;
+
+	// stolen code
+	R->EAX(frame);
+	return 0x706F6F;
+}