From 6d011e4760be6e45680b41a98b9049c1ec44c951 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Thu, 8 Oct 2015 00:06:21 +0200
Subject: [PATCH] Ask the Lua script for number of channels.

---
 mixer.cpp |  4 ++--
 theme.cpp | 26 ++++++++++++++++++--------
 theme.h   |  2 ++
 theme.lua |  2 +-
 4 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/mixer.cpp b/mixer.cpp
index 99aa33c..ce3d04e 100644
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -422,8 +422,8 @@ void Mixer::thread_func()
 		live_frame.temp_textures = { rgba_tex };
 		output_channel[OUTPUT_LIVE].output_frame(live_frame);
 
-		// Set up non-live inputs.
-		for (unsigned i = 1; i < 4; ++i) {  // FIXME: Don't lock to 4, ask Lua.
+		// Set up preview and any additional channels.
+		for (unsigned i = 1; i < theme->get_num_channels() + 2; ++i) {
 			DisplayFrame display_frame;
 			pair<EffectChain *, function<void()>> chain = theme->get_chain(i, frame / 60.0f, WIDTH, HEIGHT);  // FIXME: dimensions
 			display_frame.chain = chain.first;
diff --git a/theme.cpp b/theme.cpp
index 5d42c3d..31eb23d 100644
--- a/theme.cpp
+++ b/theme.cpp
@@ -191,14 +191,24 @@ Theme::Theme(const char *filename, ResourcePool *resource_pool)
 	register_class("LiveInputWrapper", LiveInputWrapper_funcs); 
 	register_class("WhiteBalanceEffect", WhiteBalanceEffect_funcs); 
 
-        // Run script.
-        lua_settop(L, 0);
-        if (luaL_dofile(L, filename)) {
-                fprintf(stderr, "error: %s\n", lua_tostring(L, -1));
-                lua_pop(L, 1);
-                exit(1);
-        }
-        assert(lua_gettop(L) == 0); 
+	// Run script.
+	lua_settop(L, 0);
+	if (luaL_dofile(L, filename)) {
+		fprintf(stderr, "error: %s\n", lua_tostring(L, -1));
+		lua_pop(L, 1);
+		exit(1);
+	}
+	assert(lua_gettop(L) == 0);
+
+	// Ask it for the number of channels.
+	lua_getglobal(L, "num_channels");
+
+	if (lua_pcall(L, 0, 1, 0) != 0) {
+		fprintf(stderr, "error running function `num_channels': %s", lua_tostring(L, -1));
+		exit(1);
+	}
+
+	num_channels = luaL_checknumber(L, 1);
 }
 
 void Theme::register_class(const char *class_name, const luaL_Reg *funcs)
diff --git a/theme.h b/theme.h
index f58681d..473985a 100644
--- a/theme.h
+++ b/theme.h
@@ -24,6 +24,7 @@ public:
 		input_textures[signal_num].tex_y = tex_y;
 		input_textures[signal_num].tex_cbcr = tex_cbcr;
 	}
+	int get_num_channels() { return num_channels; }
 
 	void connect_signal(movit::YCbCrInput *input, int signal_num);
 	void transition_clicked(int transition_num, float t);
@@ -35,6 +36,7 @@ private:
 	struct {
 		GLuint tex_y = 0, tex_cbcr = 0;
 	} input_textures[16];  // FIXME
+	int num_channels;
 };
 
 class LiveInputWrapper {
diff --git a/theme.lua b/theme.lua
index fbe2cbf..82339f8 100644
--- a/theme.lua
+++ b/theme.lua
@@ -30,7 +30,7 @@ simple_chain:finalize(false);
 -- Returns the number of outputs in addition to the live (0) and preview (1).
 -- Called only once, at the start of the program.
 function num_channels()
-	return 0;
+	return 2;
 end
 
 -- Called every frame.
-- 
2.39.2