Basic waterfall scroll

scripts/loaders/sprite_loader.gd

@@ -233,6 +233,9 @@ func snes_load_worldmap(rom: File):
 			image = snes_mode7_compressed_to_tile(tiledata, tile_palettes[tile])
 			tile_images.append(image)
 			# tile_textures.append(texture_from_image(image))
+		if world_ts == 0:  # Waterfall hack: lay it out vertically, pushing out dummy tiles
+			tile_images[0x97] = tile_images[0x88]
+			tile_images[0x98] = tile_images[0x87]
 		worldmap_tile_individual_imgs.append(tile_images)
 		worldmap_tile_atlas_textures.append(texture_from_image(make_tile_atlas(tile_images)))
 

shaders/worldmap_shader.gdshader

@@ -3,11 +3,18 @@ uniform sampler2D tile_atlas : hint_normal;
 uniform sampler2D palette : hint_normal;
 // uniform float tile_width = 8.0;
 uniform float tilemap_width = 512.0;  // Require square tilemap for now
+uniform bool enable_sea_scroll = true;  // Disable on underwater maps (tileset 3)
+uniform bool enable_waterfall_scroll = true;  // Only enable on tileset 1
 const float index_scale = 255.0 / 16.0;
 const vec2 sea_tile_uv = vec2(0.125, 0.375);
 const vec2 sea_tile_uv_end = vec2(0.25, 0.5);
 const vec2 sea_tile_size = sea_tile_uv_end - sea_tile_uv;
 const vec2 sea_tile_size_inv = 1.0/sea_tile_size;
+const vec2 waterfall_tile_uv = vec2(7.0/16.0, 8.0/16.0);
+const vec2 waterfall_tile_uv_end = vec2(9.0/16.0, 9.0/16.0);
+const vec2 waterfall_tile_uv_end_hack = vec2(9.0/16.0, 10.0/16.0);  // we hack a second row in the atlas
+const vec2 waterfall_tile_size = waterfall_tile_uv_end - waterfall_tile_uv;
+const vec2 waterfall_tile_size_inv = 1.0/waterfall_tile_size;
 
 // This shader maps from tileID texels to Tiles, and then applies palette.
 // tiles hardcoded to 16x16 tiles for now
@@ -24,7 +31,7 @@ vec2 get_tile_atlas_uv(float tile_id, vec2 uv) {
 
 	// Sea HScroll tile UV modulation
 	// Make this branchless later
-	if (all(greaterThanEqual(out_uv, sea_tile_uv)) && all(lessThan(out_uv, sea_tile_uv_end))) {
+	if (enable_sea_scroll && all(greaterThanEqual(out_uv, sea_tile_uv)) && all(lessThan(out_uv, sea_tile_uv_end))) {
 		vec2 sea_tile_uv_diff = out_uv - sea_tile_uv;
 		vec2 pos = sea_tile_uv_diff * sea_tile_size_inv;
 		// Silly warpy effects
@@ -39,7 +46,18 @@ vec2 get_tile_atlas_uv(float tile_id, vec2 uv) {
 		pos.x = fract(pos.x - TIME/4.267 + (pos.y * (9.0/16.0)));
 		out_uv = mix(sea_tile_uv, sea_tile_uv_end, pos);
 	}
-	// TODO: waterfall VScroll UV modulation
+	// Waterfall VScroll UV modulation
+	// This has a super annoying property of being a 2tall tile scroll laid out horizontally
+	// In sprite_loader we hack the atlas such that we can just vscroll each one
+	if (enable_waterfall_scroll && all(greaterThanEqual(out_uv, waterfall_tile_uv)) && all(lessThan(out_uv, waterfall_tile_uv_end))) {
+		vec2 waterfall_tile_uv_diff = out_uv - waterfall_tile_uv;
+		vec2 pos = waterfall_tile_uv_diff * waterfall_tile_size_inv;
+		// Real animation seems to scroll in a cycle of shift col 1px, next frame, shift col 1px, next frame, increment by 4 rows twice, shift that one, repeat
+		// 1, 1, 5, 5, 3, 3, 7, 7, 2, 2, 6, 6, 4, 4, 8, 8
+		// For now, don't bother about the double increment
+		pos.y = fract((pos.y - TIME*1.3 + (pos.x * (4.5/32.0))) * 0.5);
+		out_uv = mix(waterfall_tile_uv, waterfall_tile_uv_end_hack, pos);
+	}
 
 	return out_uv;
 }

worldmap_palette_mat.tres

@@ -5,3 +5,5 @@
 [resource]
 shader = ExtResource( 1 )
 shader_param/tilemap_width = 512.0
+shader_param/enable_sea_scroll = true
+shader_param/enable_waterfall_scroll = true