initHEADmain

1 files changed, 187 insertions, 0 deletions

diff --git a/mod/pan.c b/mod/pan.c
new file mode 100644
index 0000000..84a0551
--- /dev/null
+++ b/mod/pan.c
@@ -0,0 +1,187 @@
+/*
+ * melisma - extensible and scriptable audio engine
+ * Copyright (C) 2026  Ludvig Gunne Lindström
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <lauxlib.h>
+#include "melisma.h"
+#include "mutil.h"
+
+#define PAN_TYPENAME "pan"
+
+struct pan
+{
+	ml_channel *l_out;
+	ml_channel *r_out;
+	float       val;
+	bool        map;
+};
+
+static void proc(const ml_proc_args *args)
+{
+	struct pan *pan = args->userp;
+
+	float val,*in,*l_out,*r_out,*map;
+	in = args->in[0];
+	l_out = args->out[0];
+	r_out = args->out[1];
+	map = pan->map ? args->in[1] : NULL;
+
+	for (size_t i = 0; i < args->nframes; i++)
+	{
+		val = map ? map[i] : pan->val;
+		l_out[i] = val*in[i];
+		r_out[i] = (1 - val)*in[i];
+	}
+}
+
+static int l_init(lua_State *s)
+{
+	ml_channel *dst,*src,*map_dst,*map_src = NULL;
+	float val = 0;
+
+	if (lua_isuserdata(s,1))
+	{
+		map_src = mutil_get_channel(s,1);
+	}
+	else
+	{
+		val = luaL_checknumber(s,1);
+	}
+
+	src = mutil_get_channel(s,2);
+
+	struct pan *pan = calloc(1,sizeof(*pan));
+	pan->val = val;
+	pan->map = map_src != NULL;
+
+	ml_node *node = ml_create_node(proc,pan);
+	ml_label_node(node,"pan");
+
+	dst = ml_add_input(node);
+	pan->l_out = ml_add_output(node);
+	pan->r_out = ml_add_output(node);
+
+	ml_connect(src,dst);
+
+	if (pan->map)
+	{
+		map_dst = ml_add_input(node);
+		ml_connect(map_src,map_dst);
+	}
+
+	*(void**) lua_newuserdata(s,sizeof(void*)) = pan;
+	luaL_setmetatable(s,PAN_TYPENAME);
+
+	return 1;
+}
+
+static int l_left(lua_State *s)
+{
+	struct pan *pan = *(void**) luaL_checkudata(s,1,PAN_TYPENAME);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = pan->l_out;
+	luaL_setmetatable(s,MELISMA_OUTPUT_CHANNEL_TYPENAME);
+	return 1;
+}
+
+static int l_right(lua_State *s)
+{
+	struct pan *pan = *(void**) luaL_checkudata(s,1,PAN_TYPENAME);
+	*(void**) lua_newuserdata(s,sizeof(void*)) = pan->r_out;
+	luaL_setmetatable(s,MELISMA_OUTPUT_CHANNEL_TYPENAME);
+	return 1;
+}
+
+static int l_set(lua_State *s)
+{
+	struct pan *pan = *(void**) luaL_checkudata(s,1,PAN_TYPENAME);
+	pan->val = luaL_checknumber(s,2);
+	return 0;
+}
+
+int luaopen_melisma_pan(lua_State *s)
+{
+	ml_check_version();
+
+/*** Panning
+
+	local mpan = require 'melisma.pan'
+	local mexpression = require 'melisma.expression'
+	local moscil = require 'melisma.oscil'
+
+	local wt = moscil.wavetable.sin()
+	local lfo_oscil = moscil.init(wt,1,1)
+	local lfo = (1 + mexpression.input(lfo_oscil,0) / 2):build()
+
+	local oscil = moscil.init(wt,440,0.5)
+	local pan = mpan.init(lfo,oscil)
+
+	local left = pan:left()
+	local right = pan:right()
+
+@classmod pan
+*/
+	lua_newtable(s);
+	int tbl = lua_gettop(s);
+
+/*** Initialize a panning unit.
+
+A panning value ranges from 0 to 1, where a value of 0
+will pan everything to the left.
+
+@static
+@function init
+@tparam number|channel x Constant pan or a controlling signal.
+@tparam channel sig Input signal.
+@treturn pan The newly created panning unit.
+*/
+	lua_pushcfunction(s,l_init);
+	lua_setfield(s,tbl,"init");
+
+/*** Get the left output signal.
+@function left
+@treturn channel
+*/
+	lua_pushcfunction(s,l_left);
+	lua_setfield(s,tbl,"left");
+
+
+/*** Get the right output signal.
+@function right
+@treturn channel
+*/
+	lua_pushcfunction(s,l_right);
+	lua_setfield(s,tbl,"right");
+
+/*** Set the panning value.
+@function set
+@tparam number x
+*/
+	lua_pushcfunction(s,l_set);
+	lua_setfield(s,tbl,"set");
+
+	luaL_newmetatable(s,PAN_TYPENAME);
+	int mt = lua_gettop(s);
+
+	lua_pushvalue(s,tbl);
+	lua_setfield(s,mt,"__index");
+
+	lua_settop(s,tbl);
+	return 1;
+}