From 6ff41c431132706d0f844f88df78650551aac925 Mon Sep 17 00:00:00 2001
From: past-due <30942300+past-due@users.noreply.github.com>
Date: Mon, 21 Aug 2023 18:06:15 -0400
Subject: [PATCH] Support velocity for droid dying animation effect

Based on droid's last movement direction and speed
---
 src/droid.cpp   |  9 ++++++++-
 src/effects.cpp | 16 ++++++++++++++--
 src/effects.h   |  2 +-
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/droid.cpp b/src/droid.cpp
index a8e0bde6bd1..10406411e2e 100644
--- a/src/droid.cpp
+++ b/src/droid.cpp
@@ -207,6 +207,13 @@ int droidReloadBar(const BASE_OBJECT *psObj, const WEAPON *psWeap, int weapon_sl
 
 void addDroidDeathAnimationEffect(DROID *psDroid)
 {
+	// DERIVED from moveCalcNormalSpeed and moveGetDroidPosDiffs:
+
+	uint16_t iDroidDir = psDroid->rot.direction;
+	uint16_t adiff = (uint16_t)(iDroidDir - psDroid->sMove.moveDir);  // Cast wrapping intended.
+	int move = iCosR(adiff, psDroid->sMove.speed);
+	Vector3f velocity(iSinR(iDroidDir, move), iCosR(iDroidDir, move), 0.f);
+
 	// DERIVED FROM displayComponentObject:
 
 	Vector3i position, rotation;
@@ -252,7 +259,7 @@ void addDroidDeathAnimationEffect(DROID *psDroid)
 
 			SetEffectForPlayer(psDroid->player);
 			effectSetSize(100);
-			addEffect(&position, EFFECT_DROID_ANIMEVENT_DYING, type, true, strImd, 0, graphicsTime, &rotation);
+			addEffect(&position, EFFECT_DROID_ANIMEVENT_DYING, type, true, strImd, 0, graphicsTime, &rotation, &velocity);
 		}
 	}
 }
diff --git a/src/effects.cpp b/src/effects.cpp
index dcacbd37873..00ff6d7b9c8 100644
--- a/src/effects.cpp
+++ b/src/effects.cpp
@@ -301,13 +301,20 @@ void addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool s
 	return addEffect(pos, group, type, specified, imd, lit, graphicsTime);
 }
 
-static bool updateDroidDeathAnimationEffect(const EFFECT *psEffect)
+static bool updateDroidDeathAnimationEffect(EFFECT *psEffect)
 {
 	iIMDShape *imd = psEffect->imd;
 	if (!imd)
 	{
 		return false;
 	}
+
+	/* Move it */
+	auto deltaX = graphicsTimeAdjustedIncrement(psEffect->velocity.x);
+	auto deltaY = graphicsTimeAdjustedIncrement(psEffect->velocity.y);
+	psEffect->position.x += deltaX;
+	psEffect->position.z += deltaY;
+
 	// NOTE: We actually store the timeAnimationStarted (in gameTime) in psEffect->lastFrame
 	UDWORD timeAnimationStarted = psEffect->lastFrame;
 	int objanimcycles = (imd->objanimcycles > 0) ? imd->objanimcycles : 1; // do not allow infinite looping for death animations
@@ -347,7 +354,7 @@ static void renderDroidDeathAnimationEffect(const EFFECT *psEffect, const glm::m
 	}
 }
 
-void addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, int lit, unsigned effectTime, Vector3i *rot /*= nullptr*/)
+void addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, int lit, unsigned effectTime, Vector3i *rot /*= nullptr*/, Vector3f *velocity /*= nullptr*/)
 {
 	if (gamePaused())
 	{
@@ -369,6 +376,11 @@ void addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool s
 		psEffect->rotation.z = rot->z;
 	}
 
+	if (velocity)
+	{
+		psEffect->velocity = *velocity;
+	}
+
 	/* Now, note group and type */
 	psEffect->group = group;
 	psEffect->type = type;
diff --git a/src/effects.h b/src/effects.h
index af864d89d36..1e9261644a9 100644
--- a/src/effects.h
+++ b/src/effects.h
@@ -159,7 +159,7 @@ void	initEffectsSystem();
 void	shutdownEffectsSystem();
 void	processEffects(const glm::mat4 &perspectiveViewMatrix);
 void 	addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, int lit);
-void    addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, int lit, unsigned effectTime, Vector3i *rot = nullptr);
+void    addEffect(const Vector3i *pos, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, int lit, unsigned effectTime, Vector3i *rot = nullptr, Vector3f *velocity = nullptr);
 void    addMultiEffect(const Vector3i *basePos, Vector3i *scatter, EFFECT_GROUP group, EFFECT_TYPE type, bool specified, iIMDShape *imd, unsigned int number, bool lit, unsigned int size, unsigned effectTime);
 
 void	renderEffect(const EFFECT *psEffect, const glm::mat4 &viewMatrix);