mac-syphon: Add "Allow Transparency" property

Transparency is now disabled by default, so that alpha values from
injected back buffers don't propagate to OBS (e.g. Minecraft doesn't
render properly in OBS unless "Allow Transparency" is disabled)

plugins/mac-syphon/data/locale/en-US.ini

@@ -8,3 +8,4 @@ Crop.origin.x="Crop left"
 Crop.origin.y="Crop top"
 Crop.size.width="Crop right"
 Crop.size.height="Crop bottom"
+AllowTransparency="Allow Transparency"

plugins/mac-syphon/syphon.m

@@ -17,6 +17,7 @@ struct syphon {
 	uint32_t          width, height;
 	bool              crop;
 	CGRect            crop_rect;
+	bool              allow_transparency;
 
 	obs_source_t *source;
 
@@ -465,6 +466,9 @@ static void *syphon_create_internal(obs_data_t *settings, obs_source_t *source)
 
 	load_crop(s, settings);
 
+	s->allow_transparency = obs_data_get_bool(settings,
+			"allow_transparency");
+
 	return s;
 
 fail:
@@ -836,6 +840,9 @@ static inline obs_properties_t *syphon_properties_internal(syphon_t s)
 			OBS_COMBO_TYPE_LIST, OBS_COMBO_FORMAT_STRING);
 	obs_property_set_modified_callback(list, servers_changed);
 
+	obs_properties_add_bool(props, "allow_transparency",
+			obs_module_text("AllowTransparency"));
+
 	obs_property_t *launch = obs_properties_add_button(props,
 			"launch inject", obs_module_text("LaunchSyphonInject"),
 			launch_syphon_inject);
@@ -954,6 +961,12 @@ static void syphon_video_render(void *data, gs_effect_t *effect)
 	if (!s->tex)
 		return;
 
+	bool disable_blending = !s->allow_transparency;
+	if (disable_blending) {
+		gs_enable_blending(false);
+		gs_enable_color(true, true, true, false);
+	}
+
 	gs_vertexbuffer_flush(s->vertbuffer);
 	gs_load_vertexbuffer(s->vertbuffer);
 	gs_load_indexbuffer(NULL);
@@ -968,6 +981,11 @@ static void syphon_video_render(void *data, gs_effect_t *effect)
 
 	gs_technique_end_pass(tech);
 	gs_technique_end(tech);
+
+	if (disable_blending) {
+		gs_enable_color(true, true, true, true);
+		gs_enable_blending(true);
+	}
 }
 
 static uint32_t syphon_get_width(void *data)
@@ -1094,6 +1112,9 @@ static inline bool update_syphon(syphon_t s, obs_data_t *settings)
 
 static void syphon_update_internal(syphon_t s, obs_data_t *settings)
 {
+	s->allow_transparency = obs_data_get_bool(settings,
+			"allow_transparency");
+
 	load_crop(s, settings);
 	update_inject(s, settings);
 	if (update_syphon(s, settings))