func_friction: Added implementation of a friction modifier for player entities. This affects pmove.c as well.

src/gs-entbase/shared.src

@@ -5,5 +5,6 @@
 #includelist
 shared/decals.cpp
 shared/spraylogo.cpp
+shared/func_friction.cpp
 shared/trigger_gravity.cpp
 #endlist

src/gs-entbase/shared/func_friction.cpp

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2016-2020 Marco Hladik <marco@icculus.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*QUAKED func_friction (0 .5 .8) ?
+"targetname"    Name
+"modifier"      Friction modifier.
+
+Volume that permanently adds a modifier that affects an entities' friction.
+Higher value = less friction.
+*/
+
+#ifdef CLIENT
+class func_friction:CBaseEntity
+#else
+class func_friction:CBaseTrigger
+#endif
+{
+	float m_flFriction;
+	void(void) func_friction;
+	virtual void(void) touch;
+	virtual void(void) Respawn;
+
+#ifdef CLIENT
+	virtual void(void) Initialized;
+	virtual void(string, string) SpawnKey;
+#endif
+};
+
+void func_friction::touch(void)
+{
+	other.friction = m_flFriction;
+}
+
+/* TODO: Make this redundant */
+void func_friction::Respawn(void)
+{
+	solid = SOLID_BSPTRIGGER;
+#ifdef GS_DEVELOPER
+	alpha = 0.5f;
+#endif
+}
+
+void func_friction::func_friction(void)
+{
+#ifdef SERVER
+	for (int i = 1; i < (tokenize(__fullspawndata) - 1); i += 2) {
+		switch (argv(i)) {
+		case "modifier":
+			m_flFriction = stof(argv(i+1));
+			break;
+		default:
+			break;
+		}
+	}
+	CBaseEntity::CBaseEntity();
+	CBaseTrigger::InitBrushTrigger();
+#endif
+}
+
+#ifdef CLIENT
+void func_friction::Initialized (void)
+{
+	setmodel(this, model);
+	movetype = MOVETYPE_NONE;
+	solid = SOLID_BSPTRIGGER;
+}
+void func_friction::SpawnKey(string strField, string strKey)
+{
+	switch (strField) {
+		case "modifier":
+			m_flFriction = stof(strKey);
+			break;
+		default:
+			CBaseEntity::SpawnKey(strField, strKey);
+	}
+}
+#endif

src/shared/pmove.c

@@ -382,10 +382,19 @@ PMove_AccelLadder(float move_time, float premove, vector wish_dir, float wish_sp
 void
 PMove_AccelFriction(float move_time, float premove, vector wish_dir, float wish_speed)
 {
+	float flApplyFriction;
 	float flFriction;
 	vector vecTemp;
 
-	// friction
+	flApplyFriction = serverkeyfloat("phy_friction");
+
+	/* per frame basis friction modifier */
+	if (self.friction != 0.0f) {
+		flApplyFriction /= self.friction;
+		self.friction = 0.0f;
+	}
+
+	/* apply friction */
 	if (self.velocity[0] || self.velocity[1]) {
 		vecTemp = self.velocity;
 		vecTemp[2] = 0;
@@ -398,15 +407,16 @@ PMove_AccelFriction(float move_time, float premove, vector wish_dir, float wish_
 		// apply friction
 		if (trace_fraction == 1.0) {
 			if (flFriction < serverkeyfloat("phy_stopspeed")) {
-				flFriction = 1 - move_time * (serverkeyfloat("phy_stopspeed") / flFriction) * serverkeyfloat("phy_friction") * serverkeyfloat("phy_edgefriction");
+				flFriction = 1 - move_time * (serverkeyfloat("phy_stopspeed") / flFriction) * flApplyFriction * serverkeyfloat("phy_edgefriction");
 			} else {
-				flFriction = 1 - move_time * serverkeyfloat("phy_friction") * serverkeyfloat("phy_edgefriction");
+				flFriction = 1 - move_time * flApplyFriction * serverkeyfloat("phy_edgefriction");
 			}
 		} else {
 			if (flFriction < serverkeyfloat("phy_stopspeed")) {
-				flFriction = 1 - move_time * (serverkeyfloat("phy_stopspeed") / flFriction) * serverkeyfloat("phy_friction");
+				flFriction = 1 - move_time * (serverkeyfloat("phy_stopspeed") / flFriction) * flApplyFriction;
 			} else {
-				flFriction = 1 - move_time * serverkeyfloat("phy_friction");
+				
+				flFriction = 1 - move_time * flApplyFriction;
 			}
 		}