Add per-player shadow direction override via set_lighting

doc/lua_api.md

@@ -9147,6 +9147,11 @@ child will follow movement and rotation of that bone.
         * `intensity` sets the intensity of the shadows from 0 (no shadows, default) to 1 (blackness)
         * `tint` tints the shadows with the provided color, with RGB values ranging from 0 to 255.
           (default `{r=0, g=0, b=0}`)
+        * `direction` is a direction vector that can override the direction of the light,
+          disregarding the sun/moon position. This is useful for custom skyboxes.
+          The default is a zero vector and disables the override.
+          Note: the vector points "outwards" so that `(0, 1, 0)` is equivalent to
+          the sun at midday shining straight down.
       * `exposure` is a table that controls automatic exposure.
         The basic exposure factor equation is `e = 2^exposure_correction / clamp(luminance, 2^luminance_min, 2^luminance_max)`
         * This has no effect on clients who have the "Automatic Exposure" effect disabled.

src/client/game.cpp

@@ -3591,17 +3591,23 @@ void Game::updateShadows()
 
 	float in_timeofday = std::fmod(runData.time_of_day_smooth, 1.0f);
 
-	float timeoftheday = getWickedTimeOfDay(in_timeofday);
-	bool is_day = timeoftheday > 0.25 && timeoftheday < 0.75;
-	bool is_shadow_visible = is_day ? sky->getSunVisible() : sky->getMoonVisible();
 	const auto &lighting = client->getEnv().getLocalPlayer()->getLighting();
-	shadow->setShadowIntensity(is_shadow_visible ? lighting.shadow_intensity : 0.0f);
 	shadow->setShadowTint(lighting.shadow_tint);
 
-	timeoftheday = std::fmod(timeoftheday + 0.75f, 0.5f) + 0.25f;
 	const float offset_constant = 10000.0f;
 
-	v3f light = is_day ? sky->getSunDirection() : sky->getMoonDirection();
+	v3f light;
+	if (lighting.shadow_direction.getLengthSQ() > 0.0f) {
+		// Custom shadow direction: bypass sun/moon visibility check
+		shadow->setShadowIntensity(lighting.shadow_intensity);
+		light = lighting.shadow_direction;
+	} else {
+		float timeoftheday = getWickedTimeOfDay(in_timeofday);
+		bool is_day = timeoftheday > 0.25f && timeoftheday < 0.75f;
+		bool is_shadow_visible = is_day ? sky->getSunVisible() : sky->getMoonVisible();
+		shadow->setShadowIntensity(is_shadow_visible ? lighting.shadow_intensity : 0.0f);
+		light = is_day ? sky->getSunDirection() : sky->getMoonDirection();
+	}
 
 	v3f sun_pos = light * offset_constant;
 	shadow->getDirectionalLight().setDirection(sun_pos);

src/lighting.h

@@ -4,6 +4,7 @@
 
 #pragma once
 #include "SColor.h"
+#include "irr_v3d.h"
 
 
 /**
@@ -51,4 +52,5 @@ struct Lighting
 	float bloom_intensity {0.05f};
 	float bloom_strength_factor {1.0f};
 	float bloom_radius {1.0f};
+	v3f shadow_direction;
 };

src/network/clientpackethandler.cpp

@@ -1875,5 +1875,10 @@ void Client::handleCommand_SetLighting(NetworkPacket *pkt)
 		*pkt >> lighting.bloom_intensity
 				>> lighting.bloom_strength_factor
 				>> lighting.bloom_radius;
+
+		if (!pkt->hasRemainingBytes())
+			break;
+		// >= 5.16.0-dev
+		*pkt >> lighting.shadow_direction;
 	} while (0);
 }

src/network/networkprotocol.h

@@ -692,6 +692,13 @@ enum ToClientCommand : u16
 			f32 speed_dark_bright
 			f32 speed_bright_dark
 			f32 center_weight_power
+		f32 volumetric_light_strength
+		SColor shadow_tint
+		bloom parameters
+			f32 bloom_intensity
+			f32 bloom_strength_factor
+			f32 bloom_radius
+		v3f shadow_direction ({0,0,0} = unset)
 	*/
 
 	TOCLIENT_SPAWN_PARTICLE_BATCH = 0x64,

src/script/lua_api/l_object.cpp

@@ -2691,6 +2691,10 @@ int ObjectRef::l_set_lighting(lua_State *L)
 			lua_getfield(L, -1, "tint");
 			read_color(L, -1, &lighting.shadow_tint);
 			lua_pop(L, 1); // tint
+			lua_getfield(L, -1, "direction");
+			if (!lua_isnil(L, -1))
+				lighting.shadow_direction = check_v3f(L, -1);
+			lua_pop(L, 1); // direction
 		}
 		lua_pop(L, 1); // shadows
 
@@ -2744,6 +2748,8 @@ int ObjectRef::l_get_lighting(lua_State *L)
 	lua_setfield(L, -2, "intensity");
 	push_ARGB8(L, lighting.shadow_tint);
 	lua_setfield(L, -2, "tint");
+	push_v3f(L, lighting.shadow_direction);
+	lua_setfield(L, -2, "direction");
 	lua_setfield(L, -2, "shadows");
 	lua_pushnumber(L, lighting.saturation);
 	lua_setfield(L, -2, "saturation");

src/server.cpp

@@ -2024,6 +2024,8 @@ void Server::SendSetLighting(session_t peer_id, const Lighting &lighting)
 	pkt << lighting.bloom_intensity << lighting.bloom_strength_factor <<
 			lighting.bloom_radius;
 
+	pkt << lighting.shadow_direction;
+
 	Send(&pkt);
 }