smallpond

commit 16370512560a6e4d160ff3e15bd836f8b3fad77b
parent 5bae7b7947be0058653ceeee9c14a593c87b0c09
Author: Nihal Jere <nihal@nihaljere.xyz>
Date:   Wed, 21 Dec 2022 21:52:17 -0600

good animated curves

Diffstat:
M
main.c
 | 
12
++++++++----
M
smallpond.lua
 | 
2
+-

2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/main.c b/main.c
@@ -58,6 +58,7 @@ split_cubic(double t, double x1, double y1, double x2, double y2, double x, doub
 int
 draw_curve(lua_State *L)
 {
+	double t = lua_tonumber(L, -7);
 	double x0 = lua_tonumber(L, -6);
 	double y0 = lua_tonumber(L, -5);
 	double x1 = lua_tonumber(L, -4);
@@ -67,11 +68,14 @@ draw_curve(lua_State *L)
 
 	cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
 
-	cairo_curve_to(cr, x0, y0, x1, y1, x2, y2);
-	cairo_line_to(cr, x2, y2 + 1);
-	cairo_curve_to(cr, x1, y1 + 5, x0, y0 + 1, x0, y0 + 1);
+	double q0x, q0y, r0x, r0y, bx, by;
+	split_cubic(t, 0, 0, x1 - x0, y1 - y0, x2 - x0, y2 - y0, &q0x, &q0y, &r0x, &r0y, &bx, &by);
+	cairo_move_to(cr, x0, y0);
+	cairo_rel_curve_to(cr, q0x, q0y, r0x, r0y, bx, by);
+	split_cubic(t, 0, 1, x1 - x0, y1 + 5 - y0, x2 - x0, y2 + 1 - y0, &q0x, &q0y, &r0x, &r0y, &bx, &by);
+	cairo_rel_line_to(cr, 0, 1);
+	cairo_rel_curve_to(cr, r0x - bx, r0y - by, q0x - bx, q0y - by, q0x - bx, q0y - by);
 	cairo_line_to(cr, x0, y0);
-	cairo_set_line_width(cr, 1);
 	cairo_fill(cr);
 
 	return 0;
diff --git a/smallpond.lua b/smallpond.lua
@@ -1016,7 +1016,7 @@ function drawframe(time)
 				delta = (time - item.time.start) / (item.time.stop - item.time.start)
 			end
 			local endx = item.x0 + delta*(item.x2 - item.x0)
-			draw_curve(toff + item.x0, item.y0, toff + (item.x0 + endx) / 2, (item.y0 + item.y2) / 2 + 20, toff + endx, item.y2)
+			draw_curve(delta, toff + item.x0, item.y0, toff + (item.x0 + endx) / 2, (item.y0 + item.y2) / 2 + 20, toff + endx, item.y2)
 		elseif item.kind == "beamseg" then
 			if item.time.start > time then goto continue end
 			local delta