From 5b9e7ac7e47c59db5e2dec41d15587ab9ca10606 Mon Sep 17 00:00:00 2001
From: kichikuou <KichikuouChrome@gmail.com>
Date: Sat, 26 Nov 2022 13:47:40 +0900
Subject: [PATCH] ReignEngine: Correctly mark transparent materials

There are two types of transparent materials: materials that have an
alpha map and materials that have a color map with an alpha channel.
This change makes the latter to be considered transparent.
---
 src/3d/3d_internal.h |  1 +
 src/3d/model.c       | 19 ++++++++++++-------
 src/3d/renderer.c    |  4 ++--
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/3d/3d_internal.h b/src/3d/3d_internal.h
index c7892c5..577b50c 100644
--- a/src/3d/3d_internal.h
+++ b/src/3d/3d_internal.h
@@ -57,6 +57,7 @@ struct mesh {
 
 struct material {
 	uint32_t flags;
+	bool is_transparent;
 	GLuint color_map;
 	GLuint specular_map;
 	GLuint alpha_map;
diff --git a/src/3d/model.c b/src/3d/model.c
index 8c2918b..15ac432 100644
--- a/src/3d/model.c
+++ b/src/3d/model.c
@@ -58,7 +58,7 @@ struct archive_data *RE_get_aar_entry(struct archive *aar, const char *dir, cons
 	return dfile;
 }
 
-static GLuint load_texture(struct archive *aar, const char *path, const char *name)
+static GLuint load_texture(struct archive *aar, const char *path, const char *name, bool *has_alpha_out)
 {
 	struct archive_data *dfile = RE_get_aar_entry(aar, path, name, "");
 	if (!dfile) {
@@ -83,6 +83,8 @@ static GLuint load_texture(struct archive *aar, const char *path, const char *na
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 	glGenerateMipmap(GL_TEXTURE_2D);
 	glBindTexture(GL_TEXTURE_2D, 0);
+	if (has_alpha_out)
+		*has_alpha_out = cg->metrics.has_alpha;
 	cg_free(cg);
 	return texture;
 }
@@ -94,18 +96,21 @@ static bool init_material(struct material *material, const struct pol_material *
 		WARNING("No color texture");
 		return false;
 	}
-	material->color_map = load_texture(aar, path, m->textures[COLOR_MAP]);
+	bool has_alpha;
+	material->color_map = load_texture(aar, path, m->textures[COLOR_MAP], &has_alpha);
 	if (!material->color_map)
 		return false;
 
 	if (m->textures[SPECULAR_MAP])
-		material->specular_map = load_texture(aar, path, m->textures[SPECULAR_MAP]);
+		material->specular_map = load_texture(aar, path, m->textures[SPECULAR_MAP], NULL);
 	if (m->textures[ALPHA_MAP])
-		material->alpha_map = load_texture(aar, path, m->textures[ALPHA_MAP]);
+		material->alpha_map = load_texture(aar, path, m->textures[ALPHA_MAP], NULL);
 	if (m->textures[LIGHT_MAP])
-		material->light_map = load_texture(aar, path, m->textures[LIGHT_MAP]);
+		material->light_map = load_texture(aar, path, m->textures[LIGHT_MAP], NULL);
 	if (m->textures[NORMAL_MAP])
-		material->normal_map = load_texture(aar, path, m->textures[NORMAL_MAP]);
+		material->normal_map = load_texture(aar, path, m->textures[NORMAL_MAP], NULL);
+
+	material->is_transparent = has_alpha || material->alpha_map;
 
 	struct amt_material *amt_m = amt ? amt_find_material(amt, m->name) : NULL;
 	if (amt_m) {
@@ -442,7 +447,7 @@ struct model *model_load(struct archive *aar, const char *path)
 		}
 	}
 	for (int i = 0; i < model->nr_materials; i++) {
-		if (model->materials[i].alpha_map) {
+		if (model->materials[i].is_transparent) {
 			model->has_transparent_material = true;
 			break;
 		}
diff --git a/src/3d/renderer.c b/src/3d/renderer.c
index ee0fd49..7d74aab 100644
--- a/src/3d/renderer.c
+++ b/src/3d/renderer.c
@@ -319,7 +319,7 @@ static void render_model(struct RE_instance *inst, struct RE_renderer *r, enum d
 	for (int i = 0; i < model->nr_meshes; i++) {
 		struct mesh *mesh = &model->meshes[i];
 		struct material *material = &model->materials[mesh->material];
-		bool is_transparent = material->alpha_map || inst->alpha < 1.0f;
+		bool is_transparent = material->is_transparent || inst->alpha < 1.0f;
 		if (phase != (is_transparent ? DRAW_TRANSPARENT : DRAW_OPAQUE))
 			continue;
 
@@ -858,7 +858,7 @@ void RE_render(struct sact_sprite *sp)
 			continue;
 		render_instance(inst, r, view_transform, DRAW_OPAQUE);
 	}
-	// Render transparent instances, from nearest to farthest.
+	// Render transparent instances, from farthest to nearest.
 	for (int i = 0; i < plugin->nr_instances; i++) {
 		struct RE_instance *inst = sorted_instances[i];
 		if (!inst)