diff --git a/modules/SACT/sprite_eupdate.c b/modules/SACT/sprite_eupdate.c
index 3bcbbcc..e92a82a 100644
--- a/modules/SACT/sprite_eupdate.c
+++ b/modules/SACT/sprite_eupdate.c
@@ -55,7 +55,6 @@ typedef struct ecopyparam ecopyparam_t;
 static ecopyparam_t ecp;
 
 #include "sprite_eupdate_perspect.c"
-#include "sprite_eupdate_uneune.c"
 #include "sprite_eupdate_zmbbul.c"
 
 typedef void entrypoint (surface_t *, surface_t *);
@@ -91,7 +90,7 @@ static entrypoint *cb[39] = {
 	ec28_cb,
 	ec29_cb,
 	ec_dummy_cb,
-	ec31_cb,
+	sdl_effect_cb,
 	ec_dummy_cb,
 	ec_dummy_cb,
 	ec_dummy_cb,
diff --git a/modules/SACT/sprite_eupdate_uneune.c b/modules/SACT/sprite_eupdate_uneune.c
deleted file mode 100644
index f60b87d..0000000
--- a/modules/SACT/sprite_eupdate_uneune.c
+++ /dev/null
@@ -1,67 +0,0 @@
-static void uneune(surface_t *in, surface_t *out, int st) {
-	int r = 4 * st;
-	double th = 4 * st * M_PI;
-	int x, y, m, n;
-	
-	switch(in->depth) {
-	case 16: {
-		WORD *src, *dst;
-		for (y = 0; y < in->height; y++) {
-			for (x = 0; x < in->width; x++) {
-				m = x + r * sin(y * th / in->height);
-				n = y + r * cos(x * th / in->width);
-				src = (WORD *)GETOFFSET_PIXEL(in, m, n);
-				dst = (WORD *)GETOFFSET_PIXEL(out, x, y);
-				if ((m > 0) && (m < in->width) && (n > 0) && (n < in->height)) {
-					*dst = *src;
-				} else {
-					*dst = 0;
-				}
-			}
-		}
-	}
-	case 24:
-	case 32: {
-		DWORD *src, *dst;
-		for (y = 0; y < in->height; y++) {
-			for (x = 0; x < in->width; x++) {
-				m = x + r * sin(y * th / in->height);
-				n = y + r * cos(x * th / in->width);
-				src = (DWORD *)GETOFFSET_PIXEL(in, m, n);
-				dst = (DWORD *)GETOFFSET_PIXEL(out, x, y);
-				if ((m > 0) && (m < in->width) && (n > 0) && (n < in->height)) {
-					*dst = *src;
-				} else {
-					*dst = 0;
-				}
-			}
-		}
-	}}
-}
-
-
-
-// うねうねクロスフェード
-static void ec31_cb(surface_t *sfsrc, surface_t *sfdst) {
-	int curstep, maxstep;
-	surface_t *st, *dt;
-	
-	maxstep = 32;
-	curstep = maxstep * (ecp.curtime - ecp.sttime)/ (ecp.edtime - ecp.sttime);
-	st = sf_dup2(sfsrc, FALSE, FALSE);
-	dt = sf_dup2(sfdst, FALSE, FALSE);
-	
-	if (curstep < 16) {
-		uneune(sfsrc, st, curstep);
-		uneune(sfdst, dt, curstep);
-		gre_Blend(sf0, 0, 0, st, 0, 0, dt, 0, 0, st->width, st->height, curstep * 8);
-	} else {
-		uneune(sfsrc, st, 32-curstep);
-		uneune(sfdst, dt, 32-curstep);
-		gre_Blend(sf0, 0, 0, st, 0, 0, dt, 0, 0, st->width, st->height, curstep * 8);
-	}
-	sf_free(st);
-	sf_free(dt);
-	ags_updateFull();
-}
-
diff --git a/src/effect.h b/src/effect.h
index 672f4c9..f7f73ef 100644
--- a/src/effect.h
+++ b/src/effect.h
@@ -72,6 +72,7 @@ enum sact_effect {
 	SACT_EFFECT_ROTATE_IN        = 21,
 	SACT_EFFECT_ROTATE_OUT_CW    = 22,
 	SACT_EFFECT_ROTATE_IN_CW     = 23,
+	SACT_EFFECT_ZIGZAG_CROSSFADE = 31,
 };
 
 // Internal effect numbers.
@@ -110,6 +111,7 @@ enum sdl_effect_type {
 	EFFECT_ROTATE_IN,
 	EFFECT_ROTATE_OUT_CW,
 	EFFECT_ROTATE_IN_CW,
+	EFFECT_ZIGZAG_CROSSFADE,
 };
 
 enum sdl_effect_type from_nact_effect(enum nact_effect effect);
diff --git a/src/sdl_effect.c b/src/sdl_effect.c
index 2847682..4f43411 100644
--- a/src/sdl_effect.c
+++ b/src/sdl_effect.c
@@ -83,6 +83,7 @@ enum sdl_effect_type from_sact_effect(enum sact_effect effect) {
 	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;
+	case SACT_EFFECT_ZIGZAG_CROSSFADE: return EFFECT_ZIGZAG_CROSSFADE;
 	default:                           return EFFECT_INVALID;
 	}
 }
@@ -1004,6 +1005,88 @@ static void rotate_free(struct sdl_effect *eff) {
 	free(eff);
 }
 
+// EFFECT_ZIGZAG_CROSSFADE
+
+struct zigzag_crossfade_effect {
+	struct sdl_effect eff;
+	SDL_Texture *tmp1, *tmp2;
+};
+
+static void zigzag_crossfade_step(struct sdl_effect *eff, double progress);
+static void zigzag_crossfade_free(struct sdl_effect *eff);
+
+static struct sdl_effect *zigzag_crossfade_new(SDL_Rect *rect, SDL_Surface *old, SDL_Surface *new) {
+	if (!SDL_RenderTargetSupported(sdl_renderer))
+		return fallback_effect_new(rect, old, new, EFFECT_ZIGZAG_CROSSFADE);
+
+	struct zigzag_crossfade_effect *eff = calloc(1, sizeof(struct zigzag_crossfade_effect));
+	if (!eff)
+		NOMEMERR();
+	effect_init(&eff->eff, rect, old, new, EFFECT_ZIGZAG_CROSSFADE);
+	eff->tmp1 = SDL_CreateTexture(sdl_renderer, SDL_PIXELFORMAT_RGB888, SDL_TEXTUREACCESS_TARGET, rect->w, rect->h);
+	eff->tmp2 = SDL_CreateTexture(sdl_renderer, SDL_PIXELFORMAT_RGB888, SDL_TEXTUREACCESS_TARGET, rect->w, rect->h);
+	eff->eff.step = zigzag_crossfade_step;
+	eff->eff.finish = zigzag_crossfade_free;
+	return &eff->eff;
+}
+
+static void wave_warp_h(SDL_Texture *src, SDL_Texture *dst, int w, int h, double amplitude, double length, double phase) {
+	SDL_SetRenderTarget(sdl_renderer, dst);
+	SDL_SetRenderDrawColor(sdl_renderer, 0, 0, 0, 255);
+	SDL_RenderClear(sdl_renderer);
+	SDL_Rect sr = {0, 0, w, 1};
+	SDL_Rect dr = {0, 0, w, 1};
+	for (int y = 0; y < h; y++) {
+		sr.y = dr.y = y;
+		dr.x = sin(phase + y * (2 * M_PI / 360 * length)) * amplitude;
+		SDL_RenderCopy(sdl_renderer, src, &sr, &dr);
+	}
+	SDL_SetRenderTarget(sdl_renderer, NULL);
+}
+
+static void wave_warp_v(SDL_Texture *src, SDL_Texture *dst, int w, int h, double amplitude, double length, double phase) {
+	SDL_SetRenderTarget(sdl_renderer, dst);
+	SDL_SetRenderDrawColor(sdl_renderer, 0, 0, 0, 255);
+	SDL_RenderClear(sdl_renderer);
+	SDL_Rect sr = {0, 0, 1, h};
+	SDL_Rect dr = {0, 0, 1, h};
+	for (int x = 0; x < w; x++) {
+		sr.x = dr.x = x;
+		dr.y = sin(phase + x * (2 * M_PI / 360 * length)) * amplitude;
+		SDL_RenderCopy(sdl_renderer, src, &sr, &dr);
+	}
+	SDL_SetRenderTarget(sdl_renderer, NULL);
+}
+
+static void zigzag_crossfade_step(struct sdl_effect *eff, double progress) {
+	struct zigzag_crossfade_effect *this = (struct zigzag_crossfade_effect *)eff;
+
+	double amp = (progress < 0.5 ? progress : 1.0 - progress) * 80;
+	double len = (progress < 0.5 ? progress : 1.0 - progress) * 20;
+	double phase = progress * 10;
+
+	wave_warp_h(eff->tx_old, this->tmp1, eff->dst_rect.w, eff->dst_rect.h, amp, len, phase);
+	wave_warp_v(this->tmp1, this->tmp2, eff->dst_rect.w, eff->dst_rect.h, amp, len, phase);
+	SDL_RenderCopy(sdl_renderer, this->tmp2, NULL, &eff->dst_rect);
+
+	wave_warp_h(eff->tx_new, this->tmp1, eff->dst_rect.w, eff->dst_rect.h, amp, len, phase);
+	wave_warp_v(this->tmp1, this->tmp2, eff->dst_rect.w, eff->dst_rect.h, amp, len, phase);
+	SDL_SetTextureBlendMode(this->tmp2, SDL_BLENDMODE_BLEND);
+	SDL_SetTextureAlphaMod(this->tmp2, progress * 255);
+	SDL_RenderCopy(sdl_renderer, this->tmp2, NULL, &eff->dst_rect);
+	SDL_SetTextureBlendMode(this->tmp2, SDL_BLENDMODE_NONE);
+
+	SDL_RenderPresent(sdl_renderer);
+}
+
+static void zigzag_crossfade_free(struct sdl_effect *eff) {
+	struct zigzag_crossfade_effect *this = (struct zigzag_crossfade_effect *)eff;
+	SDL_DestroyTexture(this->tmp1);
+	SDL_DestroyTexture(this->tmp2);
+	effect_finish(&this->eff, true);
+	free(this);
+}
+
 
 static SDL_Surface *create_surface(agsurface_t *as, int x, int y, int w, int h) {
 	SDL_Surface *sf = SDL_CreateRGBSurfaceWithFormat(0, w, h, 32, SDL_PIXELFORMAT_RGB888);
@@ -1066,6 +1149,8 @@ struct sdl_effect *sdl_effect_init(SDL_Rect *rect, agsurface_t *old, int ox, int
 	case EFFECT_ROTATE_IN_CW:
 	case EFFECT_ZOOM_IN:
 		return rotate_new(rect, sf_old, sf_new, type);
+	case EFFECT_ZIGZAG_CROSSFADE:
+		return zigzag_crossfade_new(rect, sf_old, sf_new);
 	default:
 		WARNING("Unknown effect %d\n", type);
 		return crossfade_new(rect, sf_old, sf_new);