wip: prep for interpolation

modifiers/trail/trail.wren

@@ -200,15 +200,13 @@ class TrailSystem is ModifierSystem {
 	}
 
 	tick(delta) {
-
 		//System.print("positions")
 		record_positions(delta)
 		//System.print("buffers")
 		update_buffers()
 		//System.print("debug")
-		debug_draw()
+		//debug_draw()
 		//System.print("end") 
-		
 	} //tick
 
 	record_positions(delta: Num){
@@ -218,7 +216,7 @@ class TrailSystem is ModifierSystem {
 			var instance_data: TrailData = _instance_data[entity]
 
 			var pos = Transform.get_pos_world(entity)
-			var up = Transform.local_dir_to_world(entity, 0, 1, 0)
+			var up = Transform.local_dir_to_world(entity, 0, data.edge_length * 0.5, 0)
 			var prev_pos = instance_data.previous_pos || pos
 			var prev_up = instance_data.previous_up || up
 
@@ -252,8 +250,6 @@ class TrailSystem is ModifierSystem {
 			dist = dist + diff
 			var step = data.length / data.subdivisions_length
 			while(dist > step){
-				//interpolate between points
-				//todo: extrapolate curve instead of linear
 				dist = dist - step
 				var t = 1 - dist / diff
 				var point = Point.new([
@@ -266,7 +262,6 @@ class TrailSystem is ModifierSystem {
 					Math.lerp(prev_up.z, up.z, t)
 				])
 				Math.normalize(point.up)
-				//System.print(point.up)
 				if(instance_data.points.count >= data.subdivisions_length - 1) instance_data.points.dequeue()
 				instance_data.points.enqueue(point)
 			}
@@ -307,29 +302,19 @@ class TrailSystem is ModifierSystem {
 			var step = data.length / data.subdivisions_length
 
 			var point_index = -1
-			System.print("------------")
 			while(true){
 				point_index = point_index + 1
 				if(point_index >= instance_data.points.count) break
 				i = i + 1
 				var p:Point = instance_data.points[point_index]
 
-				var from: Vec
-				var from_up: Vec
-				if(point_index == 0){
-					from = Transform.get_pos_world(entity)
-					from_up = Transform.local_dir_to_world(entity, 0, 1, 0)
-				} else {
-					var prev: Point = instance_data.points[point_index-1]
-					from = prev.pos
-					from_up = prev.up
-				}
-
-				System.print(from_up)
-
+				
 				var to = p.pos
 				var to_up = p.up
 
+				var from = to
+				var from_up = to_up
+
 				var t = instance_data.progress_since_last_point / step
 				var pos_x = Math.lerp(from.x, to.x, t)
 				var pos_y = Math.lerp(from.y, to.y, t)
@@ -339,6 +324,7 @@ class TrailSystem is ModifierSystem {
 				var up_y = Math.lerp(from_up.y, to_up.y, t)
 				var up_z = Math.lerp(from_up.z, to_up.z, t)
 
+
 				pos_x = to.x
 				pos_y = to.y
 				pos_z = to.z
@@ -349,10 +335,10 @@ class TrailSystem is ModifierSystem {
 
 				var x = instance_data.points.count + 1 - i
 				for(y in 0...data.subdivisions_width){
-					var t = 1 - y / (data.subdivisions_width-1)
-					var offset_x = Math.lerp(-p.up.x, p.up.x, t)
-					var offset_y = Math.lerp(-p.up.y, p.up.y, t)
-					var offset_z = Math.lerp(-p.up.z, p.up.z, t)
+					var t = y / (data.subdivisions_width-1)
+					var offset_x = Math.lerp(-up_x, up_x, t)
+					var offset_y = Math.lerp(-up_y, up_y, t)
+					var offset_z = Math.lerp(-up_z, up_z, t)
 					positions[x*4*data.subdivisions_width + y*4 + 0] = pos_x + offset_x * data.edge_length * 0.5
 					positions[x*4*data.subdivisions_width + y*4 + 1] = pos_y + offset_y * data.edge_length * 0.5
 					positions[x*4*data.subdivisions_width + y*4 + 2] = pos_z + offset_z * data.edge_length * 0.5