diff --git a/Makefile b/Makefile
index 43e4eab..66f2ed3 100644
--- a/Makefile
+++ b/Makefile
@@ -472,6 +472,7 @@ CL_OBJS := \
 	keys.o		\
 	menu.o		\
 	r_efrag.o	\
+	r_model.o	\
 	r_part.o	\
 	sbar.o		\
 	snd_dma.o	\
diff --git a/common/gl_rmain.c b/common/gl_rmain.c
index b88f557..8cb3320 100644
--- a/common/gl_rmain.c
+++ b/common/gl_rmain.c
@@ -517,10 +517,9 @@ static void
 R_AliasSetupSkin(entity_t *e, aliashdr_t *pahdr)
 {
     int skinnum;
-    int i, frame, numframes;
+    int frame, numframes;
     maliasskindesc_t *pskindesc;
-    float *pskinintervals, fullinterval;
-    float targettime, time;
+    float *intervals;
     GLuint *glt;
 
     skinnum = e->skinnum;
@@ -534,21 +533,9 @@ R_AliasSetupSkin(entity_t *e, aliashdr_t *pahdr)
     frame = pskindesc->firstframe;
     numframes = pskindesc->numframes;
 
-    /*
-     * when loading in Mod_LoadAliasSkinGroup, we guaranteed all interval
-     * values are positive, so we don't have to worry about division by 0
-     */
     if (numframes > 1) {
-	pskinintervals = (float *)((byte *)pahdr + pahdr->skinintervals);
-	pskinintervals += frame;
-	fullinterval = pskinintervals[numframes - 1];
-	time = cl.time + e->syncbase;
-	targettime = time - ((int)(time / fullinterval)) *  fullinterval;
-	for (i = 0; i < numframes - 1; i++) {
-	    if (pskinintervals[i] > targettime)
-		break;
-	}
-	frame += i;
+	intervals = (float *)((byte *)pahdr + pahdr->skinintervals) + frame;
+	frame += Mod_FindInterval(intervals, numframes, cl.time + e->syncbase);
     }
 
     glt = (GLuint *)((byte *)pahdr + pahdr->skindata);
@@ -564,8 +551,8 @@ R_SetupAliasFrame
 static void
 R_SetupAliasFrame(const entity_t *e, aliashdr_t *pahdr)
 {
-    int i, frame, pose, numposes;
-    float time, targettime, fullinterval, *intervals;
+    int frame, pose, numposes;
+    float *intervals;
 
     frame = e->frame;
     if ((frame >= pahdr->numframes) || (frame < 0)) {
@@ -577,16 +564,8 @@ R_SetupAliasFrame(const entity_t *e, aliashdr_t *pahdr)
     numposes = pahdr->frames[frame].numposes;
 
     if (numposes > 1) {
-	intervals = (float *)((byte *)pahdr + pahdr->poseintervals);
-	intervals += pose;
-	fullinterval = intervals[numposes - 1];
-	time = cl.time + e->syncbase;
-	targettime = time - (int)(time / fullinterval) % numposes;
-	for (i = 0; i < numposes - 1; i++) {
-	    if (intervals[i] > targettime)
-		break;
-	}
-	pose += i;
+	intervals = (float *)((byte *)pahdr + pahdr->poseintervals) + pose;
+	pose += Mod_FindInterval(intervals, numposes, cl.time + e->syncbase);
     }
 
     GL_DrawAliasFrame(pahdr, pose);
diff --git a/common/r_alias.c b/common/r_alias.c
index 34a8c51..40abbb8 100644
--- a/common/r_alias.c
+++ b/common/r_alias.c
@@ -628,10 +628,9 @@ static void
 R_AliasSetupSkin(entity_t *e, aliashdr_t *pahdr)
 {
     int skinnum;
-    int i, frame, numframes, skinbytes;
+    int frame, numframes, skinbytes;
     maliasskindesc_t *pskindesc;
-    float *pskinintervals, fullinterval;
-    float targettime, time;
+    float *intervals;
     byte *pdata;
 
     skinnum = e->skinnum;
@@ -647,21 +646,9 @@ R_AliasSetupSkin(entity_t *e, aliashdr_t *pahdr)
     frame = pskindesc->firstframe;
     numframes = pskindesc->numframes;
 
-    /*
-     * when loading in Mod_LoadAliasSkinGroup, we guaranteed all interval
-     * values are positive, so we don't have to worry about division by 0
-     */
     if (numframes > 1) {
-	pskinintervals = (float *)((byte *)pahdr + pahdr->skinintervals);
-	pskinintervals += frame;
-	fullinterval = pskinintervals[numframes - 1];
-	time = cl.time + e->syncbase;
-	targettime = time - ((int)(time / fullinterval)) *  fullinterval;
-	for (i = 0; i < numframes - 1; i++) {
-	    if (pskinintervals[i] > targettime)
-		break;
-	}
-	frame += i;
+	intervals = (float *)((byte *)pahdr + pahdr->skinintervals) + frame;
+	frame += Mod_FindInterval(intervals, numframes, cl.time + e->syncbase);
     }
 
     skinbytes = pahdr->skinwidth * pahdr->skinheight * r_pixbytes;
@@ -763,8 +750,8 @@ set r_apverts
 static void
 R_AliasSetupFrame(entity_t *e, aliashdr_t *pahdr)
 {
-    int i, frame, pose, numposes;
-    float time, targettime, fullinterval, *intervals;
+    int frame, pose, numposes;
+    float *intervals;
 
     frame = e->frame;
     if ((frame >= pahdr->numframes) || (frame < 0)) {
@@ -775,21 +762,9 @@ R_AliasSetupFrame(entity_t *e, aliashdr_t *pahdr)
     pose = pahdr->frames[frame].firstpose;
     numposes = pahdr->frames[frame].numposes;
 
-//
-// when loading in Mod_LoadAliasGroup, we guaranteed all interval values
-// are positive, so we don't have to worry about division by 0
-//
     if (numposes > 1) {
-	intervals = (float *)((byte *)pahdr + pahdr->poseintervals);
-	intervals += pose;
-	fullinterval = intervals[numposes - 1];
-	time = cl.time + e->syncbase;
-	targettime = time - (int)(time / fullinterval) * fullinterval;
-	for (i = 0; i < numposes - 1; i++) {
-	    if (intervals[i] > targettime)
-		break;
-	}
-	pose += i;
+	intervals = (float *)((byte *)pahdr + pahdr->poseintervals) + pose;
+	pose += Mod_FindInterval(intervals, numposes, cl.time + e->syncbase);
     }
 
 #ifdef NQ_HACK
diff --git a/common/r_model.c b/common/r_model.c
new file mode 100644
index 0000000..5785c90
--- /dev/null
+++ b/common/r_model.c
@@ -0,0 +1,44 @@
+/*
+Copyright (C) 1996-1997 Id Software, Inc.
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+
+// Shared model functions for renderers
+
+/*
+ * Find the correct interval based on time
+ * Used for Alias model frame/sprite/skin group animations
+ */
+int
+Mod_FindInterval(const float *intervals, int numintervals, float time)
+{
+    int i;
+    float fullinterval, targettime;
+
+    /*
+     * when loading models/skins/sprites, we guaranteed all interval values
+     * are positive, so we don't have to worry about division by 0
+     */
+    fullinterval = intervals[numintervals - 1];
+    targettime = time - (int)(time / fullinterval) * fullinterval;
+    for (i = 0; i < numintervals - 1; i++)
+	if (intervals[i] > targettime)
+	    break;
+
+    return i;
+}
diff --git a/include/model.h b/include/model.h
index 252ff34..49c92d8 100644
--- a/include/model.h
+++ b/include/model.h
@@ -482,4 +482,6 @@ void Mod_LoadSpriteModel(model_t *mod, void *buffer, const char *loadname);
 
 mspriteframe_t *Mod_GetSpriteFrame(struct entity_s *e, msprite_t *psprite, float time);
 
+int Mod_FindInterval(const float *intervals, int numintervals, float time);
+
 #endif /* MODEL_H */