From ce29ce6ad108d66001d900d64266bded757a2666 Mon Sep 17 00:00:00 2001
From: _ <_@_>
Date: Mon, 21 Feb 2022 00:44:03 +0000
Subject: [PATCH] converting a very simple two-mesh GLB to IQM

---
 Cargo.lock  | 277 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 Cargo.toml  |   2 +
 src/main.rs | 155 +++++++++++++++++++----------
 3 files changed, 383 insertions(+), 51 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 58ecb14..be8a6db 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,15 +2,292 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "adler32"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aae1277d39aeec15cb388266ecc24b11c80469deae6067e17a1a7aa9e5c1f234"
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "base64"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3441f0f7b02788e948e47f457ca01f1d7e6d92c693bc132c22b087d3141c03ff"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "bytemuck"
+version = "1.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "439989e6b8c38d1b6570a384ef1e49c8848128f5a97f3914baef02920842712f"
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
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+checksum = "3d7b894f5411737b7867f4827955924d7c254fc9f4d91a6aad6b097804b1018b"
+
+[[package]]
+name = "crc32fast"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b540bd8bc810d3885c6ea91e2018302f68baba2129ab3e88f32389ee9370880d"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "deflate"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73770f8e1fe7d64df17ca66ad28994a0a623ea497fa69486e14984e715c5d174"
+dependencies = [
+ "adler32",
+ "byteorder",
+]
+
+[[package]]
+name = "glam"
+version = "0.20.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e4fa84eead97d5412b2a20aed4d66612a97a9e41e08eababdb9ae2bf88667490"
+
+[[package]]
+name = "gltf"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "00e0a0eace786193fc83644907097285396360e9e82e30f81a21e9b1ba836a3e"
+dependencies = [
+ "base64",
+ "byteorder",
+ "gltf-json",
+ "image",
+ "lazy_static",
+]
+
+[[package]]
+name = "gltf-derive"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bdd53d6e284bb2bf02a6926e4cc4984978c1990914d6cd9deae4e31cf37cd113"
+dependencies = [
+ "inflections",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "gltf-json"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9949836a9ec5e7f83f76fb9bbcbc77f254a577ebbdb0820867bc11979ef97cad"
+dependencies = [
+ "gltf-derive",
+ "serde",
+ "serde_derive",
+ "serde_json",
+]
+
+[[package]]
+name = "image"
+version = "0.23.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24ffcb7e7244a9bf19d35bf2883b9c080c4ced3c07a9895572178cdb8f13f6a1"
+dependencies = [
+ "bytemuck",
+ "byteorder",
+ "color_quant",
+ "jpeg-decoder",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+ "png",
+]
+
+[[package]]
+name = "inflections"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a257582fdcde896fd96463bf2d40eefea0580021c0712a0e2b028b60b47a837a"
+
+[[package]]
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+checksum = "1aab8fc367588b89dcee83ab0fd66b72b50b72fa1904d7095045ace2b0c81c35"
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
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+checksum = "791daaae1ed6889560f8c4359194f56648355540573244a5448a83ba1ecc7435"
+dependencies = [
+ "adler32",
+]
+
 [[package]]
 name = "model_converter"
 version = "0.1.0"
 dependencies = [
  "byteorder",
+ "glam",
+ "gltf",
 ]
+
+[[package]]
+name = "num-integer"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2cc698a63b549a70bc047073d2949cce27cd1c7b0a4a862d08a8031bc2801db"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-iter"
+version = "0.1.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2021c8337a54d21aca0d59a92577a029af9431cb59b909b03252b9c164fad59"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "12ac428b1cb17fce6f731001d307d351ec70a6d202fc2e60f7d4c5e42d8f4f07"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
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+version = "0.16.8"
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+dependencies = [
+ "bitflags",
+ "crc32fast",
+ "deflate",
+ "miniz_oxide",
+]
+
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+ "unicode-xid",
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+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "ryu"
+version = "1.0.9"
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+
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+
+[[package]]
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+checksum = "08597e7152fcd306f41838ed3e37be9eaeed2b61c42e2117266a554fab4662f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e8d9fa5c3b304765ce1fd9c4c8a3de2c8db365a5b91be52f186efc675681d95"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.86"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a65b3f4ffa0092e9887669db0eae07941f023991ab58ea44da8fe8e2d511c6b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
diff --git a/Cargo.toml b/Cargo.toml
index 2cee40e..f6da9e7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,3 +7,5 @@ edition = "2021"
 
 [dependencies]
 byteorder = "1.4.3"
+glam = "0.20.2"
+gltf = "1.0.0"
diff --git a/src/main.rs b/src/main.rs
index 28c35c8..05d821c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,59 +3,111 @@ use std::{
 	io::Write,
 };
 
+use glam::{
+	Mat4,
+	Vec3,
+};
+
 fn main () {
-	let vertexes = [
-		[-1.0, -1.0, -1.0],
-		[ 1.0, -1.0, -1.0],
-		[ 1.0,  1.0, -1.0],
-		[-1.0,  1.0, -1.0],
-		
-		[-1.0, -1.0,  1.0],
-		[ 1.0, -1.0,  1.0],
-		[ 1.0,  1.0,  1.0],
-		[-1.0,  1.0,  1.0],
-	];
+	let (document, buffers, _images) = gltf::import ("input.glb").unwrap ();
+	let buffer = buffers.get (0).unwrap ();
 	
-	let triangles = [
-		[0, 2, 1],
-		[0, 3, 2],
+	let mut vertexes = Vec::default ();
+	let mut triangles = Vec::default ();
+	let mut meshes = Vec::default ();
+	let mut texts = String::default ();
+	
+	for node in document.nodes () {
+		let mesh = match node.mesh () {
+			None => continue,
+			Some (x) => x,
+		};
 		
-		[0, 5, 1],
-		[1, 6, 2],
-		[2, 7, 3],
-		[3, 4, 0],
+		let m = gltf_node_get_mat4 (&node);
 		
-		[0, 4, 5],
-		[1, 5, 6],
-		[2, 6, 7],
-		[3, 7, 4],
-		
-		[4, 6, 5],
-		[4, 7, 6],
-	];
+		for prim in mesh.primitives () {
+			assert_eq! (prim.mode (), gltf::mesh::Mode::Triangles);
+			
+			let indices = prim.indices ().unwrap ();
+			let indices_view = indices.view ().unwrap ();
+			let indices_offset = indices.offset () + indices_view.offset ();
+			let indices_slice = &buffer [indices_offset..(indices_offset + indices.count () * 2)];
+			
+			let pos = prim.get (&gltf::Semantic::Positions).unwrap ();
+			let pos_view = pos.view ().unwrap ();
+			let pos_offset = pos.offset () + pos_view.offset ();
+			let pos_slice = &buffer [pos_offset..(pos_offset + pos.count () * 4 * 3)];
+			
+			let first_vertex = vertexes.len ();
+			
+			let mesh = iqm::Mesh {
+				name: u32::try_from (texts.len ()).unwrap (),
+				material: 0,
+				first_vertex: u32::try_from (first_vertex).unwrap (),
+				num_vertexes: u32::try_from (indices_slice.len () / 2).unwrap (),
+				// num_vertexes: u32::try_from (3).unwrap (),
+				first_triangle: u32::try_from (triangles.len ()).unwrap (),
+				num_triangles: u32::try_from (indices_slice.len () / 6).unwrap (),
+				//num_triangles: u32::try_from (1).unwrap (),
+			};
+			texts.push_str ("\0");
+			
+			meshes.push (mesh);
+			
+			for chunk in indices_slice.chunks_exact (2 * 3) {
+				let read_idx = |i: usize| u16::from_le_bytes ([chunk [i * 2 + 0], chunk [i * 2 + 1]]);
+				
+				let idxs = [
+					read_idx (0),
+					read_idx (1),
+					read_idx (2),
+				];
+				
+				let read_pos_coord = |i| f32::from_le_bytes ([
+					pos_slice [i * 4 + 0],
+					pos_slice [i * 4 + 1],
+					pos_slice [i * 4 + 2],
+					pos_slice [i * 4 + 3],
+				]);
+				
+				let read_pos = move |i| {
+					let i = usize::try_from (i).unwrap ();
+					m.transform_point3 (Vec3::new (
+						read_pos_coord (i * 3 + 0),
+						read_pos_coord (i * 3 + 1),
+						read_pos_coord (i * 3 + 2),
+					))
+				};
+				
+				let verts = [
+					read_pos (idxs [0]),
+					read_pos (idxs [2]),
+					read_pos (idxs [1]),
+				];
+				
+				let tri_start = u32::try_from (vertexes.len ()).unwrap ();
+				triangles.push ([
+					tri_start + 0,
+					tri_start + 1,
+					tri_start + 2,
+				]);
+				
+				for v in verts {
+					vertexes.push (v.to_array ());
+				}
+			}
+		}
+	}
+	
+	let vertexes = vertexes;
+	let triangles = triangles;
+	let meshes = meshes;
+	let texts = texts;
 	
 	let num_vertexes = u32::try_from (vertexes.len ()).unwrap ();
 	let num_triangles = u32::try_from (triangles.len ()).unwrap ();
 	
-	let mut texts = Vec::default ();
-	
-	let mesh = iqm::Mesh {
-		name: u32::try_from (texts.len ()).unwrap (),
-		material: 0,
-		first_vertex: 0,
-		num_vertexes,
-		first_triangle: 0,
-		num_triangles,
-	};
-	texts.push ("Cube");
-	
-	let meshes = vec! [
-		mesh,
-	];
-	
-	let num_text: usize = texts.iter ()
-	.map (|s| s.len () + 1)
-	.sum ();
+	let num_text = texts.len ();
 	let num_text = u32::try_from (num_text).unwrap ();
 	
 	let num_meshes = u32::try_from (meshes.len ()).unwrap ();
@@ -69,7 +121,7 @@ fn main () {
 	
 	let filesize = ofs_text + num_text;
 	
-	let mut f = File::create ("cube.iqm").unwrap ();
+	let mut f = File::create ("output.iqm").unwrap ();
 	
 	f.write_all (b"INTERQUAKEMODEL\0").unwrap ();
 	
@@ -151,7 +203,7 @@ fn main () {
 	f.write_all (&(3u32.to_le_bytes ())).unwrap ();
 	
 	// offset
-	f.write_all (&(0xA8u32.to_le_bytes ())).unwrap ();
+	f.write_all (&((ofs_vertexarrays + 5 * 4 * 1).to_le_bytes ())).unwrap ();
 	
 	// Vertexes
 	
@@ -170,10 +222,11 @@ fn main () {
 	}
 	
 	// Text
-	for s in texts {
-		f.write_all (s.as_bytes ()).unwrap ();
-		f.write_all (b"\0").unwrap ();
-	}
+	f.write_all (texts.as_bytes ()).unwrap ();
+}
+
+fn gltf_node_get_mat4 (node: &gltf::Node) -> Mat4 {
+	Mat4::from_cols_array_2d (&node.transform ().matrix ())
 }
 
 /// IQM structures as written to disk