From 639fa5993f09233549234982532d68c74f6ea5ac Mon Sep 17 00:00:00 2001
From: Elias Fleckenstein <eliasfleckenstein@web.de>
Date: Sun, 17 Apr 2022 21:16:08 +0200
Subject: [PATCH] Fix blending issues

---
 src/client/model.c       |  5 ++---
 src/client/terrain_gfx.c | 20 +++++++++++++++-----
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/src/client/model.c b/src/client/model.c
index c770d1c..5f7dd17 100644
--- a/src/client/model.c
+++ b/src/client/model.c
@@ -18,7 +18,6 @@ static List scene_new;
 static pthread_mutex_t lock_scene_new;
 static GLint units;
 
-// fixme: blending issues still occur
 static int cmp_batch_texture(const ModelBatchTexture *ta, const ModelBatchTexture *tb)
 {
 	return
@@ -130,7 +129,7 @@ static ModelNode *clone_node(ModelNode *original, ModelNode *parent)
 
 static int cmp_model(const Model *model, const f32 *distance)
 {
-	return f32_cmp(&model->distance, distance);
+	return -f32_cmp(&model->distance, distance);
 }
 
 static void render_model(Model *model)
@@ -421,7 +420,7 @@ void model_node_add_batch(ModelNode *node, ModelBatch *batch)
 
 	size_t num_meshes = ceil((double) batch->textures.siz / (double) units);
 	array_grw(&node->meshes, num_meshes);
-	ModelMesh *meshes = node->meshes.ptr + node->meshes.siz - num_meshes;
+	ModelMesh *meshes = &((ModelMesh *) node->meshes.ptr)[node->meshes.siz - num_meshes];
 
 	for (size_t m = 0; m < num_meshes; m++) {
 		ModelMesh *mesh = &meshes[m];
diff --git a/src/client/terrain_gfx.c b/src/client/terrain_gfx.c
index a855221..bf9fd98 100644
--- a/src/client/terrain_gfx.c
+++ b/src/client/terrain_gfx.c
@@ -16,6 +16,7 @@ typedef struct {
 	bool visible;
 	bool transparent;
 	ModelBatch *batch;
+	ModelBatch *batch_transparent;
 	TerrainChunk *chunk;
 	v3s32 chunkp;
 	TerrainChunk *nbrs[6];
@@ -121,8 +122,12 @@ static inline void render_node(ChunkRenderData *data, v3s32 offset)
 			data->visible = true;
 		}
 
-		if (def->visibility == VISIBILITY_BLEND)
+		ModelBatch *batch = data->batch;
+
+		if (def->visibility == VISIBILITY_BLEND) {
 			data->transparent = true;
+			batch = data->batch_transparent;
+		}
 
 		for (args.v = 0; args.v < 6; args.v++) {
 			args.vertex.cube = cube_vertices[args.f][args.v];
@@ -132,7 +137,7 @@ static inline void render_node(ChunkRenderData *data, v3s32 offset)
 			if (def->render)
 				def->render(&args);
 
-			model_batch_add_vertex(data->batch, def->tiles.textures[args.f]->txo, &args.vertex);
+			model_batch_add_vertex(batch, def->tiles.textures[args.f]->txo, &args.vertex);
 		}
 	}
 }
@@ -157,6 +162,7 @@ static Model *create_chunk_model(TerrainChunk *chunk, bool animate)
 		.visible = false,
 		.transparent = false,
 		.batch = model_batch_create(&model_shader, &terrain_vertex_layout, offsetof(TerrainVertex, textureIndex)),
+		.batch_transparent = model_batch_create(&model_shader, &terrain_vertex_layout, offsetof(TerrainVertex, textureIndex)),
 		.chunk = chunk,
 		.chunkp = v3s32_scale(chunk->pos, CHUNK_SIZE),
 		.nbrs = {NULL},
@@ -167,8 +173,9 @@ static Model *create_chunk_model(TerrainChunk *chunk, bool animate)
 	CHUNK_ITERATE
 		render_node(&data, (v3s32) {x, y, z});
 
-	if (!data.batch->textures.siz) {
+	if (!data.batch->textures.siz && !data.batch_transparent->textures.siz) {
 		model_batch_free(data.batch);
+		model_batch_free(data.batch_transparent);
 		return NULL;
 	}
 
@@ -186,10 +193,13 @@ static Model *create_chunk_model(TerrainChunk *chunk, bool animate)
 	model->root->pos = v3f32_add(v3s32_to_f32(data.chunkp), center_offset);
 	model->root->scale = (v3f32) {0.0f, 0.0f, 0.0f};
 
-	if (data.visible)
+	if (data.visible) {
 		model_node_add_batch(model->root, data.batch);
-	else
+		model_node_add_batch(model->root, data.batch_transparent);
+	} else {
 		model_batch_free(data.batch);
+		model_batch_free(data.batch_transparent);
+	}
 
 	return model;
 }
-- 
2.44.0