Didn't end up adding GPU buffers, but I made the RenderableModel class.

This class clones all the data from iqm::Model that's needed to draw
a mesh / model safely, so I can draw it without unsafe. It can be
upgraded mostly in-place to use GPU buffers later on.

src/bin/pumpkin.rs

@@ -227,8 +227,7 @@ fn main () {
 	let model_data = load_small_file ("pumpking.iqm", 1024 * 1024);
 	let model = Model::from_slice (&model_data [..]);
 	
-	let pumpkin_verts = glezz::VertexBuffer::from_slice (model.get_vertex_slice (0));
+	let renderable_model = glezz::RenderableModel::from_iqm (&model);
-	let pumpkin_indexes = glezz::IndexBuffer::from_slice (model.get_index_slice (0));
 	
 	let sky_data = load_small_file ("sky-sphere.iqm", 1024 * 1024);
 	let sky_model = Model::from_slice (&sky_data [..]);
@@ -311,35 +310,18 @@ fn main () {
 		glezz::uniform_matrix_4fv (unis ["mvp"], &mvp_mat);
 		glezz::uniform_3fv (unis ["object_space_light"], &object_space_light);
 		
-		// This stuff actually still is unsafe because it's reading
+		renderable_model.draw (&attrs, 0);
-		// right from RAM I can still access. Using a VBO here
-		// might actually make it easier to make it safe.
 		
-		if false {
+		glezz::uniform_3fv (unis ["albedo"], &green);
-			unsafe {
+		renderable_model.draw (&attrs, 1);
-				point_to_model (&attrs, &model);
-				
-				gl::DrawElements (gl::TRIANGLES, (model.meshes [0].num_triangles * 3) as i32, gl::UNSIGNED_INT, &model.get_index_slice (0) [0] as *const u8 as *const c_void);
-			}
-		}
-		
-		unsafe {
-			gl::BindBuffer (gl::ARRAY_BUFFER, 0);
-			gl::BindBuffer (gl::ELEMENT_ARRAY_BUFFER, 0);
-		}
-		
-		if true {
-			glezz::uniform_3fv (unis ["albedo"], &green);
-			
-			unsafe {
-				point_to_model (&attrs, &model);
-				
-				gl::DrawElements (gl::TRIANGLES, (model.meshes [1].num_triangles * 3) as i32, gl::UNSIGNED_INT, &model.get_index_slice (1) [0] as *const u8 as *const c_void);
-			}
-		}
 		
 		let draw_sky = true;
 		if draw_sky {
+			unsafe {
+				gl::BindBuffer (gl::ARRAY_BUFFER, 0);
+				gl::BindBuffer (gl::ELEMENT_ARRAY_BUFFER, 0);
+			}
+			
 			glezz::uniform_matrix_4fv (unis ["mvp"], &sky_mvp_mat);
 			glezz::uniform_3fv (unis ["albedo"], &white);
 			glezz::uniform_3fv (unis ["min_bright"], &white);

src/glezz.rs

@@ -1,6 +1,6 @@
 // Trivial wrappers around GLESv2 C functions that should be safe
 
-use byteorder::{LittleEndian, ReadBytesExt};
+use byteorder::{ByteOrder, LittleEndian, ReadBytesExt};
 use glam::{Mat4, Vec3, Vec4};
 use std::collections::*;
 use std::convert::TryInto;
@@ -69,41 +69,25 @@ pub fn uniform_matrix_4fv (uni: i32, m: &Mat4) {
 	}
 }
 
-// More abstract stuff
+// More abstract things
 
-unsafe fn vertex_attrib_pointer (id: Option <u32>, num_coords: i32, slice: &[u8]) {
+// Only contains f32 floats
-	const FALSE_U8: u8 = 0;
-	const FLOAT_SIZE: i32 = 4;
-	
-	if let Some (id) = id {
-		gl::VertexAttribPointer (id, num_coords, gl::FLOAT, FALSE_U8, FLOAT_SIZE * num_coords, &slice [0] as *const u8 as *const c_void);
-	}
-}
-
-pub fn draw_model (
-	attrs: &HashMap <String, Option <u32>>,
-	model: &iqm::Model, 
-	mesh_number: usize
-) {
-	let index_slice: &[u8] = model.get_index_slice (mesh_number);
-	let num_indexes = model.meshes [mesh_number].num_triangles * 3;
-	
-	unsafe {
-		vertex_attrib_pointer (attrs ["pos"], 3, model.get_vertex_slice (0));
-		vertex_attrib_pointer (attrs ["uv"], 2, model.get_vertex_slice (1));
-		vertex_attrib_pointer (attrs ["normal"], 3, model.get_vertex_slice (2));
-		
-		gl::DrawElements (gl::TRIANGLES, (num_indexes) as i32, gl::UNSIGNED_INT, &index_slice [0] as *const u8 as *const c_void);
-	}
-}
 
 pub struct VertexBuffer {
 	id: u32,
+	// Not bytes. 
 	len: usize,
+	// Assuming arrays are packed, not interleaved
+	// Typically 3, or 2 for UV.
+	num_coords: i32,
 }
 
 impl VertexBuffer {
-	pub fn from_slice (slice: &[u8]) -> Self {
+	pub fn from_slice (slice: &[u8], num_coords: i32) -> Self {
+		const FLOAT_SIZE: usize = 4;
+		
+		assert_eq! (slice.len () % (FLOAT_SIZE * (num_coords as usize)), 0);
+		
 		let id = {
 			let mut id = 0;
 			unsafe {
@@ -119,6 +103,7 @@ impl VertexBuffer {
 		Self {
 			id,
 			len: slice.len (),
+			num_coords,
 		}
 	}
 	
@@ -145,6 +130,7 @@ impl Drop for VertexBuffer {
 
 pub struct IndexBuffer {
 	id: u32,
+	// Not bytes. Number of indexes.
 	len: usize,
 	min: u32,
 	max: u32,
@@ -157,9 +143,11 @@ impl IndexBuffer {
 		let mut min = None;
 		let mut max = None;
 		
-		assert_eq! (slice.len () % 4, 0);
+		const IDX_SIZE: usize = 4;
 		
-		for _ in 0..slice.len () / 4 {
+		assert_eq! (slice.len () % IDX_SIZE, 0);
+		
+		for _ in 0..slice.len () / IDX_SIZE {
 			let idx = rdr.read_u32::<LittleEndian> ().unwrap ();
 			
 			min = match min {
@@ -187,7 +175,7 @@ impl IndexBuffer {
 		
 		Self {
 			id,
-			len: slice.len () / 4,
+			len: slice.len () / IDX_SIZE,
 			min: min.unwrap (),
 			max: max.unwrap (),
 		}
@@ -214,4 +202,88 @@ impl Drop for IndexBuffer {
 	}
 }
 
+// Takes ownership of mesh stuff in an opaque way that's abstract
+// from the IQM model. IQM is zero-copy, but this is not.
+// Since it's opaque, I can drop in a VBO/IBO setup when I'm not lazy.
 
+struct RenderableMesh {
+	first_triangle: usize,
+	num_triangles: i32,
+}
+
+pub struct RenderableModel {
+	pos: Vec <f32>,
+	uv: Vec <f32>,
+	normals: Vec <f32>,
+	
+	indexes: Vec <u32>,
+	
+	meshes: Vec <RenderableMesh>,
+}
+
+unsafe fn vertex_attrib_pointer (id: Option <u32>, num_coords: i32, slice: &[f32]) {
+	const FALSE_U8: u8 = 0;
+	const FLOAT_SIZE: i32 = 4;
+	
+	if let Some (id) = id {
+		gl::VertexAttribPointer (id, num_coords, gl::FLOAT, FALSE_U8, FLOAT_SIZE * num_coords, &slice [0] as *const f32 as *const c_void);
+	}
+}
+
+impl RenderableModel {
+	pub fn from_iqm (model: &iqm::Model) -> RenderableModel {
+		let pos_bytes = model.get_vertex_slice (iqm::types::POSITION);
+		let mut pos_vec = vec! [0.0; pos_bytes.len () / 4];
+		LittleEndian::read_f32_into (pos_bytes, &mut pos_vec [..]);
+		
+		let uv_bytes = model.get_vertex_slice (iqm::types::TEXCOORD);
+		let mut uv_vec = vec! [0.0; uv_bytes.len () / 4];
+		LittleEndian::read_f32_into (uv_bytes, &mut uv_vec [..]);
+		
+		let normal_bytes = model.get_vertex_slice (iqm::types::NORMAL);
+		let mut normal_vec = vec! [0.0; normal_bytes.len () / 4];
+		LittleEndian::read_f32_into (normal_bytes, &mut normal_vec [..]);
+		
+		let index_slice = model.get_all_indexes ();
+		
+		const IDX_SIZE: usize = 4;
+		
+		let mut indexes = vec! [0; index_slice.len () / IDX_SIZE];
+		LittleEndian::read_u32_into (index_slice, &mut indexes [..]);
+		
+		let max_index: usize = (*indexes.iter ().max ().unwrap ()).try_into ().unwrap ();
+		
+		assert! (max_index * 3 < pos_vec.len ());
+		assert! (max_index * 2 < uv_vec.len ());
+		assert! (max_index * 3 < normal_vec.len ());
+		
+		let meshes = model.meshes.iter ()
+		.map (|mesh| RenderableMesh {
+			first_triangle: mesh.first_triangle.try_into ().unwrap (),
+			num_triangles: mesh.num_triangles.try_into ().unwrap (),
+		})
+		.collect ();
+		
+		Self {
+			pos: pos_vec,
+			uv: uv_vec,
+			normals: normal_vec,
+			
+			indexes: indexes,
+			meshes,
+		}
+	}
+	
+	pub fn draw (&self, attrs: &HashMap <String, Option <u32>>, mesh_num: usize) 
+	{
+		let mesh = &self.meshes [mesh_num];
+		
+		unsafe {
+			vertex_attrib_pointer (attrs ["pos"], 3, &self.pos);
+			vertex_attrib_pointer (attrs ["uv"], 2, &self.uv);
+			vertex_attrib_pointer (attrs ["normal"], 3, &self.normals);
+			
+			gl::DrawElements (gl::TRIANGLES, mesh.num_triangles * 3, gl::UNSIGNED_INT, &self.indexes [mesh.first_triangle * 3] as *const u32 as *const c_void);
+		}
+	}
+}

src/iqm.rs

@@ -36,15 +36,15 @@ mod consts {
 	pub const OFS_EXTENSIONS: usize    = 26;
 }
 
-mod types {
+pub mod types {
-	pub const POSITION: u32     = 0;
+	pub const POSITION: usize     = 0;
-	pub const TEXCOORD: u32     = 1;
+	pub const TEXCOORD: usize     = 1;
-	pub const NORMAL: u32       = 2;
+	pub const NORMAL: usize       = 2;
-	pub const TANGENT: u32      = 3;
+	pub const TANGENT: usize      = 3;
-	pub const BLENDINDEXES: u32 = 4;
+	pub const BLENDINDEXES: usize = 4;
-	pub const BLENDWEIGHTS: u32 = 5;
+	pub const BLENDWEIGHTS: usize = 5;
-	pub const COLOR: u32        = 6;
+	pub const COLOR: usize        = 6;
-	pub const CUSTOM: u32       = 0x10;
+	pub const CUSTOM: usize       = 0x10;
 }
 
 pub mod formats {
@@ -255,4 +255,16 @@ impl <'a> Model <'a> {
 		
 		&self.data [offset..offset + num_bytes]
 	}
+	
+	pub fn get_all_indexes (&self) -> &[u8] {
+		let bytes_per_u32 = 4;
+		let indexes_per_tri = 3;
+		let stride = bytes_per_u32 * indexes_per_tri;
+		
+		let offset: usize = self.header.fields [consts::OFS_TRIANGLES].try_into ().unwrap ();
+		
+		let num_bytes: usize = (stride * self.header.fields [consts::NUM_TRIANGLES]).try_into ().unwrap ();
+		
+		&self.data [offset..offset + num_bytes]
+	}
 }