diff --git a/modules/NIGHTDLL/sprite_eupdate.c b/modules/NIGHTDLL/sprite_eupdate.c
index 17799e9..f625228 100644
--- a/modules/NIGHTDLL/sprite_eupdate.c
+++ b/modules/NIGHTDLL/sprite_eupdate.c
@@ -61,7 +61,6 @@ static ecopyparam_t ecp;
 
 // #include "sprite_eupdate_perspect.c"
 // #include "sprite_eupdate_mosaic.c"
-// #include "sprite_eupdate_aff.c"
 // #include "sprite_eupdate_uneune.c"
 #include "sprite_eupdate_buller.c"
 // #include "sprite_eupdate_zmbbul.c"
diff --git a/modules/SACT/sprite_eupdate.c b/modules/SACT/sprite_eupdate.c
index 8e20d6d..90396c5 100644
--- a/modules/SACT/sprite_eupdate.c
+++ b/modules/SACT/sprite_eupdate.c
@@ -64,7 +64,6 @@ static ecopyparam_t ecp;
 
 #include "sprite_eupdate_perspect.c"
 #include "sprite_eupdate_mosaic.c"
-#include "sprite_eupdate_aff.c"
 #include "sprite_eupdate_uneune.c"
 #include "sprite_eupdate_buller.c"
 #include "sprite_eupdate_zmbbul.c"
@@ -91,10 +90,10 @@ static entrypoint *cb[39] = {
 	sdlfader_cb,
 	ec_dummy_cb,  // 欠番
 	ec19_cb,
-	ec20_cb,
-	ec21_cb,
-	ec22_cb,
-	ec23_cb,
+	sdlfader_cb,
+	sdlfader_cb,
+	sdlfader_cb,
+	sdlfader_cb,
 	ec_dummy_cb,
 	ec25_cb,
 	ec26_cb,
@@ -364,8 +363,9 @@ int sp_eupdate(int type, int time, int cancel) {
 	
 	sfdst = sf_dup(sf0);
 	
-	if (SACT_EFFECT_PENTAGRAM_IN_OUT <= type && type <= SACT_EFFECT_HEXAGRAM_OUT_IN)
-		ecp.fader = sdl_fader_init(0, 0, sfsrc->width, sfsrc->height, 0, 0, from_sact_effect(type));
+	enum sdl_effect sdl_effect = from_sact_effect(type);
+	if (sdl_effect != EFFECT_INVALID)
+		ecp.fader = sdl_fader_init(0, 0, sfsrc->width, sfsrc->height, 0, 0, sdl_effect);
 	else
 		sf_copyall(sf0, sfsrc); // 全部の効果タイプにこの処理は要らないんだけど
 
diff --git a/modules/SACT/sprite_eupdate_aff.c b/modules/SACT/sprite_eupdate_aff.c
deleted file mode 100644
index 682403c..0000000
--- a/modules/SACT/sprite_eupdate_aff.c
+++ /dev/null
@@ -1,102 +0,0 @@
-// アフィン変換 (回転)
-
-static void do_aff(surface_t *in, surface_t *out, int deg, double zx, double zy) {
-	int xs = in->width  / 2;
-	int ys = in->height / 2;
-	double r = deg * M_PI / 180;
-	double c = cos(r);
-	double s = sin(r);
-	double x, y;
-	int i, j, m, n;
-	
-	switch(in->depth) {
-	case 16: {
-		WORD *src, *dst;
-		
-		for (i = -ys; i < ys; i++) {
-			for (j = -xs; j < xs; j++) {
-				y = (j * s + i * c) / zy;
-				x = (j * c - i * s) / zx;
-				if (y > 0) m = (int)y;
-				else       m = (int)(y -1);
-				if (x > 0) n = (int)x;
-				else       n = (int)(x -1);
-				src = (WORD *)GETOFFSET_PIXEL(in,  n+xs, m+ys);
-				dst = (WORD *)GETOFFSET_PIXEL(out, j+xs, i+ys);
-				if ((m >= -ys) && (m < ys) && (n >= -xs) && (n < xs)) {
-					*dst = *src;
-				}
-			}
-		}
-		break;
-	}
-	case 24:
-	case 32: {
-		DWORD *src, *dst;
-		
-		for (i = -ys; i < ys; i++) {
-			for (j = -xs; j < xs; j++) {
-				y = (j * s + i * c) / zy;
-				x = (j * c - i * s) / zx;
-				if (y > 0) m = (int)y;
-				else       m = (int)(y -1);
-				if (x > 0) n = (int)x;
-				else       n = (int)(x -1);
-				src = (DWORD *)GETOFFSET_PIXEL(in,  n+xs, m+ys);
-				dst = (DWORD *)GETOFFSET_PIXEL(out, j+xs, i+ys);
-				if ((m >= -ys) && (m < ys) && (n >= -xs) && (n < xs)) {
-					*dst = *src;
-				}
-			}
-		}
-		break;
-	}}
-}
-
-
-
-//回転アウト
-static void ec20_cb(surface_t *sfsrc, surface_t *sfdst) {
-	//１回転だけ
-	int maxstep, curstep;
-	maxstep = 360;
-	curstep = maxstep * (ecp.curtime - ecp.sttime)/ (ecp.edtime - ecp.sttime);
-	sf_copyall(sf0, sfdst);
-	do_aff(sfsrc, sf0, curstep, 1- (double)curstep / maxstep, 1- (double)curstep / maxstep);
-	ags_updateFull();
-	ecp.oldstep = curstep;
-}
-
-//回転イン
-static void ec21_cb(surface_t *sfsrc, surface_t *sfdst) {
-	int maxstep, curstep;
-	maxstep = 360;
-	curstep = maxstep * (ecp.curtime - ecp.sttime)/ (ecp.edtime - ecp.sttime);
-	sf_copyall(sf0, sfsrc);
-	do_aff(sfdst, sf0, curstep, (double)curstep / maxstep, (double)curstep / maxstep);
-	ags_updateFull();
-	ecp.oldstep = curstep;
-}
-
-//回転アウト(時計回り)
-static void ec22_cb(surface_t *sfsrc, surface_t *sfdst) {
-	int maxstep, curstep;
-	maxstep = 360;
-	curstep = maxstep * (ecp.curtime - ecp.sttime)/ (ecp.edtime - ecp.sttime);
-	sf_copyall(sf0, sfdst);
-	do_aff(sfsrc, sf0, -curstep, 1- (double)curstep / maxstep, 1- (double)curstep / maxstep);
-	ags_updateFull();
-	ecp.oldstep = curstep;
-}
-
-//回転イン(時計回り)
-static void ec23_cb(surface_t *sfsrc, surface_t *sfdst) {
-	int maxstep, curstep;
-	maxstep = 360;
-	curstep = maxstep * (ecp.curtime - ecp.sttime)/ (ecp.edtime - ecp.sttime);
-	sf_copyall(sf0, sfsrc);
-	do_aff(sfdst, sf0, -curstep, (double)curstep / maxstep, (double)curstep / maxstep);
-	ags_updateFull();
-	ecp.oldstep = curstep;
-}
-
diff --git a/src/effect.h b/src/effect.h
index d4e1401..31c12b1 100644
--- a/src/effect.h
+++ b/src/effect.h
@@ -38,6 +38,10 @@ enum sact_effect {
 	SACT_EFFECT_PENTAGRAM_OUT_IN = 15,
 	SACT_EFFECT_HEXAGRAM_IN_OUT  = 16,
 	SACT_EFFECT_HEXAGRAM_OUT_IN  = 17,
+	SACT_EFFECT_ROTATE_OUT       = 20,
+	SACT_EFFECT_ROTATE_IN        = 21,
+	SACT_EFFECT_ROTATE_OUT_CW    = 22,
+	SACT_EFFECT_ROTATE_IN_CW     = 23,
 };
 
 // Internal effect numbers.
@@ -51,6 +55,10 @@ enum sdl_effect {
 	EFFECT_WINDMILL,
 	EFFECT_WINDMILL_180,
 	EFFECT_WINDMILL_360,
+	EFFECT_ROTATE_OUT,
+	EFFECT_ROTATE_IN,
+	EFFECT_ROTATE_OUT_CW,
+	EFFECT_ROTATE_IN_CW,
 };
 
 enum sdl_effect from_nact_effect(enum nact_effect effect);
diff --git a/src/sdl_fader.c b/src/sdl_fader.c
index cf866e7..6e5d043 100644
--- a/src/sdl_fader.c
+++ b/src/sdl_fader.c
@@ -53,6 +53,10 @@ enum sdl_effect from_sact_effect(enum sact_effect effect) {
 	case SACT_EFFECT_PENTAGRAM_OUT_IN: return EFFECT_PENTAGRAM_OUT_IN;
 	case SACT_EFFECT_HEXAGRAM_IN_OUT:  return EFFECT_HEXAGRAM_IN_OUT;
 	case SACT_EFFECT_HEXAGRAM_OUT_IN:  return EFFECT_HEXAGRAM_OUT_IN;
+	case SACT_EFFECT_ROTATE_OUT:       return EFFECT_ROTATE_OUT;
+	case SACT_EFFECT_ROTATE_IN:        return EFFECT_ROTATE_IN;
+	case SACT_EFFECT_ROTATE_OUT_CW:    return EFFECT_ROTATE_OUT_CW;
+	case SACT_EFFECT_ROTATE_IN_CW:     return EFFECT_ROTATE_IN_CW;
 	default:                           return EFFECT_INVALID;
 	}
 }
@@ -293,8 +297,47 @@ static void step_crossfade(struct sdl_fader *fader, int step) {
 	SDL_RenderPresent(sdl_renderer);
 }
 
+static void step_rotate(struct sdl_fader *fader, int step) {
+	SDL_Texture *bg_texture, *fg_texture;
+	double angle = step * 360.0 / SDL_FADER_MAXSTEP;
+	double scale = step / (double)SDL_FADER_MAXSTEP;
+	switch (fader->effect) {
+	case EFFECT_ROTATE_OUT:
+		scale = 1.0 - scale;
+		bg_texture = fader->tx_new;
+		fg_texture = fader->tx_old;
+		angle *= -1.0;
+		break;
+	case EFFECT_ROTATE_IN:
+		bg_texture = fader->tx_old;
+		fg_texture = fader->tx_new;
+		angle *= -1.0;
+		break;
+	case EFFECT_ROTATE_OUT_CW:
+		scale = 1.0 - scale;
+		bg_texture = fader->tx_new;
+		fg_texture = fader->tx_old;
+		break;
+	case EFFECT_ROTATE_IN_CW:
+		bg_texture = fader->tx_old;
+		fg_texture = fader->tx_new;
+		break;
+	default:
+		assert(!"Cannot happen");
+	}
+	SDL_Rect r = fader->dst_rect;
+	r.x += (1.0 - scale) * r.w / 2;
+	r.y += (1.0 - scale) * r.h / 2;
+	r.w *= scale;
+	r.h *= scale;
+	SDL_RenderCopy(sdl_renderer, bg_texture, NULL, &fader->dst_rect);
+	SDL_RenderCopyEx(sdl_renderer, fg_texture, NULL, &r, angle, NULL, SDL_FLIP_NONE);
+	SDL_RenderPresent(sdl_renderer);
+}
+
 struct sdl_fader *sdl_fader_init(int sx, int sy, int w, int h, int dx, int dy, enum sdl_effect effect) {
-	if (!SDL_RenderTargetSupported(sdl_renderer) || !HAS_SDL_RenderGeometry) {
+	if (EFFECT_PENTAGRAM_IN_OUT <= effect && effect <= EFFECT_WINDMILL_360 &&
+		(!SDL_RenderTargetSupported(sdl_renderer) || !HAS_SDL_RenderGeometry)) {
 		WARNING("Effect %d is not supported in this system. Falling back to crossfade.\n", effect);
 		effect = EFFECT_CROSSFADE;
 	}
@@ -345,6 +388,12 @@ void sdl_fader_step(struct sdl_fader *fader, int step) {
 		step_polygon_mask(fader, step);
 		break;
 #endif
+	case EFFECT_ROTATE_OUT:
+	case EFFECT_ROTATE_IN:
+	case EFFECT_ROTATE_OUT_CW:
+	case EFFECT_ROTATE_IN_CW:
+		step_rotate(fader, step);
+		break;
 	default:
 		if (step == 0)
 			WARNING("Unknown effect %d\n", fader->effect);