diff --git a/src/graphics/framebuffer.nim b/src/graphics/framebuffer.nim
index b3caebc..5f337df 100644
--- a/src/graphics/framebuffer.nim
+++ b/src/graphics/framebuffer.nim
@@ -164,15 +164,15 @@ proc set_attachments(self: Framebuffer; layer, mipmap_level: int) =
             if tex.tex_type == Tex2DArray:
                 assert layer >= 0, "Texture array layer must be specified"
                 glFramebufferTextureLayer(GL_FRAMEBUFFER, attachments[i],
-                            tex.storage.tex, mipmap_level.GLint, layer.GLint)
+                    tex.storage.tex.GLuint, mipmap_level.GLint, layer.GLint)
             elif tex.tex_type == TexCube:
                 assert layer >= 0, "Texture cube side must be specified"
                 glFramebufferTexture2D(GL_FRAMEBUFFER, attachments[i],
                     (GL_TEXTURE_CUBE_MAP_POSITIVE_X.int + layer).GLenum,
-                    tex.storage.tex, mipmap_level.GLint)
+                    tex.storage.tex.GLuint, mipmap_level.GLint)
             elif self.current_mipmap_level != mipmap_level:
                 glFramebufferTexture2D(GL_FRAMEBUFFER, attachments[i], 
-                    tex.storage.target, tex.storage.tex, mipmap_level.GLint)
+                    tex.storage.target, tex.storage.tex.GLuint, mipmap_level.GLint)
 
 proc enable*(self: Framebuffer, rect = none((int32,int32,int32,int32)),
         layer = -1, mipmap_level = 0, mark_textures = true): Framebuffer {.discardable.} =
diff --git a/src/graphics/material.nim b/src/graphics/material.nim
index af05cdc..6a21bba 100644
--- a/src/graphics/material.nim
+++ b/src/graphics/material.nim
@@ -186,8 +186,8 @@ proc delete_all_shaders*(self: Material, destroy: bool = true) =
     self.last_shader = nil
 
 proc destroy*(self: Material) =
-    for shader in values(self.shaders):
-        shader.destroy()
+    self.delete_all_shaders()
+    self.textures.clear()
 
 var id = 0
 
@@ -389,12 +389,14 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
     when not defined(release):
         self.vs_code = vs
     let vertex_shader = glCreateShader(GL_VERTEX_SHADER)
+    defer: glDeleteShader(vertex_shader)
     # TODO: make a pointer array from the unjoined strings, interleaved with "\n"
     # instead of concatenating and converting
     var vs2 = vs.cstring
     glShaderSource(vertex_shader, 1, cast[cstringArray](addr vs2), nil)
     glCompileShader(vertex_shader)
     var fragment_shader: GLuint = 0
+    defer: glDeleteShader(fragment_shader)
     template fragment:string = fragment_lines.join("\n")
     if has_fragment_shader:
         fragment_shader = glCreateShader(GL_FRAGMENT_SHADER)
@@ -404,6 +406,10 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
         glShaderSource(fragment_shader, 1, cast[cstringArray](addr fragment2), nil)
         glCompileShader(fragment_shader)
     let prog = glCreateProgram()
+    defer:
+        if prog != self.program.GLuint:
+            echo "deleting program"
+            glDeleteProgram(prog)
     glAttachShader(prog, vertex_shader)
     if fragment_shader != 0:
         glAttachShader(prog, fragment_shader)
@@ -425,7 +431,6 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
         echo vs.add_line_numbers(1)
         let error_msg = dedent &"""Error compiling vertex shader of material {material.name}
             {get_shader_info_log(vertex_shader)}"""
-        glDeleteShader(vertex_shader)
         console_error(error_msg)
         return
     if fragment_shader != 0:
@@ -435,7 +440,6 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
         let error_msg = &"Error compiling fragment shader of material {material.name}\n{gl_log}"
         # console_error fragment
         let lines = fragment.split("\n")
-        glDeleteShader(fragment_shader)
         if "ERROR: 0:" in gl_log:
             # Show engine for first error
             let line = try: error_msg.split(":")[2].parseInt except: 0
@@ -463,9 +467,6 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
         # console_error fragment
         console_error("================")
         console_error error_msg
-        glDeleteProgram(prog)
-        glDeleteShader(vertex_shader)
-        glDeleteShader(fragment_shader)
         return
 
     self.camera_render_ubo_index = glGetUniformBlockIndex(prog, "CameraRenderUniform")
@@ -517,12 +518,13 @@ proc initShader*(self: Shader, engine: MyouEngine, material: Material,
     assert self.texture_locations.len + self.cubemap_locations.len +
             extra_location_count <= self.engine.renderer.max_textures
 
-    self.program = prog
+    self.program = prog.GPUProgram
 
 proc use*(self: Shader): GLuint {.inline,discardable.} =
-    glUseProgram(self.program)
-    return self.program
+    glUseProgram(self.program.GLuint)
+    return self.program.GLuint
 
 proc destroy*(self: Shader) =
-    glDeleteProgram(self.program)
+    self.program = 0.GPUProgram
+
 
diff --git a/src/graphics/render.nim b/src/graphics/render.nim
index 60fa5d2..b3ca5d0 100644
--- a/src/graphics/render.nim
+++ b/src/graphics/render.nim
@@ -255,23 +255,22 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
     # TODO: Also check with cam_data.clipping_plane!
     
     # TODO: Select alternative mesh / LoD
-    var amesh = mesh
+    var amesh {.cursor.} = mesh
     if not (amesh.data != nil and amesh.data.loaded):
         return
     self.set_flip_normals mesh.flip
-    let data = amesh.data
-
-    # for ubo in self.bound_ubos:
-    #     if ubo != nil:
-    #         ubo.unbind()
-    # self.next_ubo = 0
+    let data {.cursor.} = amesh.data
 
     # unbindAllTextures()
 
     # Main routine for each submesh
-    # (vao may be null but that's handled later)
-    for submesh_idx, vao in data.vaos:
-        if vao == 0:
+
+    # vaos have a destructor, and `pairs` copied the value,
+    # so we either use `mpairs` or keep track of submesh_idx separately.
+    var submesh_idx = -1
+    for vao in data.vaos:
+        submesh_idx.inc
+        if vao.GLuint == 0.GLuint:
             continue
         
         if not (pass == -1 or mesh.passes[submesh_idx] == pass):
@@ -282,10 +281,10 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
         else:
             material_override
 
-        let shader = mat.get_shader(mesh)
-        if shader.program == 0:
+        let shader {.cursor.} = mat.get_shader(mesh)
+        let program = shader.use()
+        if program == 0:
             continue
-        shader.use()
         self.set_cull_face(not mat.double_sided)
         
         var ubos_to_bind: seq[UBO]
@@ -313,7 +312,7 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
         # TODO: move this UBO, consolidate with cameradata
         # TODO: update only in draw_viewport
         if shader.camera_render_ubo_index.is_valid:
-            let ubo = self.camera_render_ubo
+            let ubo {.cursor.} = self.camera_render_ubo
             ubos_to_bind.add ubo
             ubo_indices.add shader.camera_render_ubo_index
             ubo.storage(CameraRenderUniform)[0] = CameraRenderUniform(
@@ -327,7 +326,7 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
             ubos_to_update.add ubo
 
         if shader.object_ubo_index.is_valid:
-            let ubo = mesh.object_ubo
+            let ubo {.cursor.} = mesh.object_ubo
             ubos_to_bind.add ubo
             ubo_indices.add shader.object_ubo_index
             const diag = vec3(1).normalize
@@ -344,13 +343,13 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
         
         # UBOs
         for i,idx in shader.ubo_indices:
-            let ubo = shader.ubos[i]
+            let ubo {.cursor.} = shader.ubos[i]
             ubos_to_bind.add ubo
             ubo_indices.add idx
         
         ubos_to_bind.bind_all()
         for i,ubo in ubos_to_bind:
-            ubo.set_prog_index(shader.program, ubo_indices[i])
+            ubo.set_prog_index(program, ubo_indices[i])
         for ubo in ubos_to_update:
             ubo.update()
 
@@ -364,8 +363,9 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
                 textures_to_bind.add texture
             else:
                 textures_to_bind.add self.blank_texture
+        assert texture_locations.len == textures_to_bind.len
         
-        let scene = mesh.scene
+        let scene {.cursor.} = mesh.scene
         if scene != nil:
             let loc = shader.shadowmap_location
             let fb = scene.shadow_maps
@@ -389,9 +389,9 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
         
         bind_all(textures_to_bind, texture_locations)
         
-        let index_buffer = data.index_buffers[submesh_idx]
+        let index_buffer = data.index_buffers[submesh_idx].GLuint
         let num_indices = data.num_indices[submesh_idx]
-        glBindVertexArray(vao)
+        glBindVertexArray(vao.GLuint)
         if not data.use_tf:
             if index_buffer != 0:
                 glDrawElements(data.draw_method.GLenum, num_indices.GLsizei, data.index_types[submesh_idx].GLenum, cast[pointer](0))
@@ -399,7 +399,7 @@ proc draw_mesh*(self: RenderManager, mesh: Mesh, mesh2world: Mat4, cam_data: Ren
                 glDrawArrays(data.draw_method.GLenum, 0, num_indices)
         else:
             assert index_buffer == 0, "Loopback transform feedback is not compatible with indexed meshes"
-            glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, data.tf_vbos[1][submesh_idx])
+            glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, data.tf_vbos[1][submesh_idx].GLuint)
             glBeginTransformFeedback(data.draw_method.GLenum)
             glDrawArrays(data.draw_method.GLenum, 0, num_indices)
             glEndTransformFeedback()
diff --git a/src/graphics/texture.nim b/src/graphics/texture.nim
index 11a470e..fffbf06 100644
--- a/src/graphics/texture.nim
+++ b/src/graphics/texture.nim
@@ -194,11 +194,13 @@ proc newTextureStorage*(ttype: TextureType, width, height, depth: int, format: T
         # of Depth_u24_s8: GL_UNSIGNED_INT
     ts.layer = 0
     ts.tile_size = vec2(1,1)
-    glGenTextures(1, addr ts.tex)
+    var tex: GLuint
+    glGenTextures(1, addr tex)
+    ts.tex = tex.GPUTexture
     return ts
 
 proc preallocate(self: Texture) =
-    let ts = self.storage
+    let ts {.cursor.} = self.storage
     case self.tex_type:
     of Tex2D:
         # TODO: only do this if necessary
@@ -232,9 +234,7 @@ proc preallocate(self: Texture) =
         discard
 
 proc freeTextureStorage(self: Texture) =
-    if self.storage != nil:
-        glDeleteTextures(1, addr self.storage.tex)
-        self.storage = nil
+    self.storage = nil
 
 proc bind_it*(texture: Texture, reserve_slot: static[int32] = -1, needs_active_texture: static[bool] = false) =
     # TODO: rewrite for using texture arrays and/or bindless
@@ -252,7 +252,7 @@ proc bind_it*(texture: Texture, reserve_slot: static[int32] = -1, needs_active_t
         if active_texture != bound_unit:
             active_texture = bound_unit
             glActiveTexture(cast[GLenum](GL_TEXTURE0.uint32 + bound_unit.uint32))
-        var old_tex = bound_textures[bound_unit]
+        var old_tex {.cursor.} = bound_textures[bound_unit]
         if old_tex != nil:
             old_tex.storage.unit = -1
             if old_tex.storage.target.uint32 != texture.storage.target.uint32:
@@ -260,7 +260,7 @@ proc bind_it*(texture: Texture, reserve_slot: static[int32] = -1, needs_active_t
             # if old_tex.sampler_object != 0:
             #     glBindSampler(cast[GLuint](bound_unit), 0)
             bound_textures[bound_unit] = nil
-        glBindTexture(texture.storage.target, texture.storage.tex)
+        glBindTexture(texture.storage.target, texture.storage.tex.GLuint)
         # if texture.sampler_object != 0:
         #     glBindSampler(bound_unit.GLuint, texture.sampler_object)
         bound_textures[bound_unit] = texture
@@ -277,7 +277,7 @@ proc unbind*(texture: Texture) =
     if texture.storage.unit == -1:
         return
     let bound_unit = texture.storage.unit
-    var old_tex = bound_textures[bound_unit]
+    var old_tex {.cursor.} = bound_textures[bound_unit]
     assert old_tex == texture, "unexpected bound texture"
     if old_tex == texture:
         bound_textures[bound_unit] = nil
@@ -308,19 +308,17 @@ proc bind_all*(textures: seq[Texture], locations: seq[GLint]) =
             active_texture = unit
             texture.storage.unit = unit
             glActiveTexture(cast[GLenum](GL_TEXTURE0.uint32 + unit.uint32))
-            let old_tex = bound_textures[unit]
+            let old_tex {.cursor.} = bound_textures[unit]
             if old_tex != nil:
                 old_tex.storage.unit = -1
                 if old_tex.storage.target != texture.storage.target:
                     glBindTexture(old_tex.storage.target, 0)
-            glBindTexture(texture.storage.target, texture.storage.tex)
+            glBindTexture(texture.storage.target, texture.storage.tex.GLuint)
             bound_textures[unit] = texture
             inc(next_texture)
             if next_texture == max_textures:
                 next_texture = 0
         glUniform1i(locations[i], unit)
-    
-
 
 proc unbindAllTextures*() =
     for tex in bound_textures:
@@ -428,7 +426,7 @@ proc newTexture*(engine: MyouEngine, name: string,
             when defined(myouUseRenderdoc):
                 # Note: when we switch to arrays we'll have to store resolutions
                 # instead of names
-                glObjectLabel(GL_TEXTURE, self.storage.tex,
+                glObjectLabel(GL_TEXTURE, self.storage.tex.GLuint,
                             GLsizei(self.name.len), self.name.cstring)
 
 proc generateMipmap*(self: Texture) =
diff --git a/src/graphics/ubo.nim b/src/graphics/ubo.nim
index 818015f..0c58643 100644
--- a/src/graphics/ubo.nim
+++ b/src/graphics/ubo.nim
@@ -61,12 +61,14 @@ proc initUBO*[T](self: UBO, renderer: RenderManager, name: string, utype: typede
     self.binding_point = -1
 
     renderer.enqueue proc() =
-        glGenBuffers 1, addr self.buffer
-        glBindBuffer(GL_UNIFORM_BUFFER, self.buffer)
+        var buffer: GLuint
+        glGenBuffers 1, addr buffer
+        self.buffer = GPUBuffer(buffer)
+        glBindBuffer(GL_UNIFORM_BUFFER, buffer)
         glBufferData(GL_UNIFORM_BUFFER, cast[GLsizeiptr](self.byte_storage.byte_len), nil, GL_DYNAMIC_DRAW)
         # glBindBuffer(GL_UNIFORM_BUFFER, 0)
         when defined(myouUseRenderdoc):
-            glObjectLabel(GL_BUFFER, self.buffer, GLsizei(name.len), name.cstring)
+            glObjectLabel(GL_BUFFER, buffer, GLsizei(name.len), name.cstring)
     return self
 
 template storage*[T](self: UBO, utype: typedesc[T]): ArrRef[T] = self.byte_storage.to(T)
@@ -83,16 +85,17 @@ proc resize*[T](self: UBO, utype: typedesc[T], count: int) =
         # but I'm deleting and unbinding the buffer just in case
         self.unbind()
         self.byte_storage = newArrRef[T](count).to(byte)
-        glDeleteBuffers 1, addr self.buffer
-        glGenBuffers 1, addr self.buffer
-        glBindBuffer(GL_UNIFORM_BUFFER, self.buffer)
+        var buffer: GLuint
+        glGenBuffers 1, addr buffer
+        self.buffer = GPUBuffer(buffer)
+        glBindBuffer(GL_UNIFORM_BUFFER, buffer)
         # TODO: set nil instead of the actual buffer,
         # and avoid using it until it's updated for the first time
         glBufferData(GL_UNIFORM_BUFFER, cast[GLsizeiptr](self.byte_storage.len), self.byte_storage.toPointer, GL_DYNAMIC_DRAW)
         # glBindBuffer(GL_UNIFORM_BUFFER, 0)
         when defined(myouUseRenderdoc):
             let name = self.name & "*" # asterisk = it was resized
-            glObjectLabel(GL_BUFFER, self.buffer, GLsizei(name.len), name.cstring)
+            glObjectLabel(GL_BUFFER, buffer, GLsizei(name.len), name.cstring)
 
 proc newUBO*[T](renderer: RenderManager, name: string, utype: typedesc[T], count: int = 1): UBO =
     var ubo = new UBO
@@ -126,9 +129,9 @@ proc bind_it*(self: UBO, rebind = false) =
         if next_ubo == self.renderer.max_uniform_buffer_bindings:
             next_ubo = 0
         self.renderer.next_ubo = next_ubo
-        glBindBufferBase(GL_UNIFORM_BUFFER, self.binding_point.GLuint, self.buffer)
+        glBindBufferBase(GL_UNIFORM_BUFFER, self.binding_point.GLuint, self.buffer.GLuint)
     elif rebind:
-        glBindBufferBase(GL_UNIFORM_BUFFER, self.binding_point.GLuint, self.buffer)
+        glBindBufferBase(GL_UNIFORM_BUFFER, self.binding_point.GLuint, self.buffer.GLuint)
 
 proc unbind*(self: UBO) =
     if self.binding_point != -1:
@@ -158,7 +161,7 @@ proc bind_all*(ubos: seq[UBO]) =
                 old_ubo.binding_point = -1
             renderer.bound_ubos[next_ubo] = ubo
             ubo.binding_point = next_ubo
-            glBindBufferBase(GL_UNIFORM_BUFFER, next_ubo.GLuint, ubo.buffer)
+            glBindBufferBase(GL_UNIFORM_BUFFER, next_ubo.GLuint, ubo.buffer.GLuint)
             inc(next_ubo)
             if next_ubo == maxubos:
                 next_ubo = 0
@@ -179,7 +182,7 @@ proc update*(self: UBO) {.inline.} =
     # NOTE: if this doesn't work in webgl, set a flag
     let len = self.byte_storage.len
     if len != 0:
-        glBindBuffer(GL_UNIFORM_BUFFER, self.buffer)
+        glBindBuffer(GL_UNIFORM_BUFFER, self.buffer.GLuint)
         glBufferData(GL_UNIFORM_BUFFER, len.GLsizeiptr, self.byte_storage.toPointer, GL_DYNAMIC_DRAW)
         # glBindBuffer(GL_UNIFORM_BUFFER, 0)
 
@@ -189,7 +192,7 @@ template is_valid*(block_index: GLuint): bool =
 proc destroy*(self: UBO) =
     self.unbind()
     self.byte_storage = nil
-    glDeleteBuffers 1, addr self.buffer
+    self.buffer = 0.GPUBuffer
 
 # TODO: make a function/template/macro that generates GLSL code to declare the UBO from an object
 
diff --git a/src/loaders/blend.nim b/src/loaders/blend.nim
index 78b0ea3..80f6be3 100644
--- a/src/loaders/blend.nim
+++ b/src/loaders/blend.nim
@@ -108,6 +108,7 @@ proc loadAsync(self: BlendLoader, callback: proc()) =
         self.close()
         self.resource = loadUri(self.blend_file_path,
             proc(ok, err, data: auto) =
+                self.resource = nil
                 if ok:
                     self.blend_file = openBlendFile(self.blend_file_path, data.data, data.byte_len)
                     callback()
diff --git a/src/loaders/blend_format.nim b/src/loaders/blend_format.nim
index d7dfe20..9e9576e 100644
--- a/src/loaders/blend_format.nim
+++ b/src/loaders/blend_format.nim
@@ -87,11 +87,10 @@ type
     TypeLengths = ptr UncheckedArray[uint16]
 
     FNode* = object
-        dna: TypeAttrsRef
-        blocks: FNodesByAddress
+        blend_file {.cursor.}: BlendFile
         # we have to keep a reference to this otherwise it will be GC'd
-        # TODO: remove the two pointers above to use less memory?
-        blend_file: BlendFile
+        # (but only in FNodes not referenced in the original, to avoid cycles)
+        blend_file_ref: BlendFile
 
         p: pointer
         count: uint32
@@ -285,8 +284,6 @@ proc openBlendFile*(path: string, data: pointer, len: int): BlendFile =
             p: blk.data.addr,
             tid: tid,
             count: if blk.count == 1: real_count else: blk.count,
-            dna: type_attrs,
-            blocks: node_blocks,
             blend_file: result)
         node_blocks[address] = node
         if blk.code[2] == '\0':
@@ -294,6 +291,7 @@ proc openBlendFile*(path: string, data: pointer, len: int): BlendFile =
             if t notin result.named_blocks:
                 result.named_blocks[t] = @[]
             result.named_blocks[t].add(node)
+    result.dna = type_attrs
     result.blocks = node_blocks
     result.type_names = type_names
     result.struct_to_type = struct_to_type
@@ -375,25 +373,25 @@ template get_fblock_of_node(n: FNode): ptr FBlock64 =
 proc contains*(n: FNode, name: string): bool =
     if n.p == nil:
         return
-    return name in n.dna[n.tid]
+    return name in n.blend_file.dna[n.tid]
 
 proc `[]`*(n: FNode, name: string): FNode =
     if n.p == nil:
         return
     assert not n.count.testBit(31), "This is an array, expected index instead of \"" & name & "\""
-    let a = n.dna[n.tid][name]
+    let a = n.blend_file.dna[n.tid][name]
     if a.atype != Value:
         let ptri = cast[ptr uint64](n.p+a.offset)[]
         if ptri == 0:
             return
         when defined(disallow_missing_blocks):
-            assert ptri in n.blocks, "Missing block pointing to: " & name
-        if ptri notin n.blocks:
+            assert ptri in n.blend_file.blocks, "Missing block pointing to: " & name
+        if ptri notin n.blend_file.blocks:
             # This may happen if e.g. the user has deleted an image used by a node
             # so we'll just return an invalid node
             echo "Missing block pointing to: " & name
             return
-        let blk = n.blocks[ptri]
+        let blk = n.blend_file.blocks[ptri]
         var count: uint32 = a.count
         if a.atype == PointerArray:
             # the sdna_index of this block is 0, which would give an incorrect struct size
@@ -403,13 +401,15 @@ proc `[]`*(n: FNode, name: string): FNode =
             count.setBit 31
         # use blk.count?
         var node = FNode(p: blk.p, tid: a.tid, count: count,
-            dna: n.dna, blocks: n.blocks, blend_file: n.blend_file)
+            blend_file: n.blend_file,
+            blend_file_ref: n.blend_file)
         if a.tid == B_void.uint16:
             node.tid = n.blend_file.struct_to_type[get_fblock_of_node(node).sdna_index]
         return node
     else:
         return FNode(p: n.p+a.offset, tid: a.tid, count: a.count,
-            dna: n.dna, blocks: n.blocks, blend_file: n.blend_file)
+            blend_file: n.blend_file,
+            blend_file_ref: n.blend_file)
 
 proc `[]`*(n: FNode, index: Natural): FNode =
     var count = n.count
@@ -419,16 +419,17 @@ proc `[]`*(n: FNode, index: Natural): FNode =
         let ptri = cast[ptr UncheckedArray[uint64]](n.p)[index]
         if ptri == 0:
             return
-        assert ptri in n.blocks, "Missing block"
-        let blk = n.blocks[ptri]
+        assert ptri in n.blend_file.blocks, "Missing block"
+        let blk = n.blend_file.blocks[ptri]
         return FNode(p: blk.p, tid: n.tid, count: 1,
-            dna: n.dna, blocks: n.blocks, blend_file: n.blend_file)
+            blend_file: n.blend_file,
+            blend_file_ref: n.blend_file)
     else:
         var n = n
         let size = if n.tid < BASIC_TYPE_LENGTHS.len:
             BASIC_TYPE_LENGTHS[n.tid]
         else:
-            # n.dna[n.tid]["(size)"].offset.int
+            # n.blend_file.dna[n.tid]["(size)"].offset.int
             n.blend_file.type_lengths[n.tid].int
         n.p = n.p + index * size
         n.count = 1
@@ -444,10 +445,9 @@ iterator items*(n: FNode, stride=0): FNode =
             if ptri == 0:
                 yield FNode()
                 continue
-            assert ptri in n.blocks, "Missing block"
-            let blk = n.blocks[ptri]
-            yield FNode(p: blk.p, tid: n.tid, count: 1,
-                dna: n.dna, blocks: n.blocks)
+            assert ptri in n.blend_file.blocks, "Missing block"
+            let blk = n.blend_file.blocks[ptri]
+            yield FNode(p: blk.p, tid: n.tid, count: 1)
     else:
         var n = n
         let stride = if stride == 0:
@@ -538,7 +538,7 @@ proc `$`*(n: FNode, depth=0, max_depth=3, just_name=false, dump_pointers=false):
             let kkstr = `$`(kk, depth, max_depth)
             ret.add indent & "[" & $i & "]: " & kkstr
         return ret.join "\n"
-    var attrs = toSeq(n.dna[n.tid].pairs)
+    var attrs = toSeq(n.blend_file.dna[n.tid].pairs)
     try:
         let name = n.id.name.str
         ret.add indent & "id.name: " & name
diff --git a/src/myou_engine.nim b/src/myou_engine.nim
index 875c336..fed32b3 100644
--- a/src/myou_engine.nim
+++ b/src/myou_engine.nim
@@ -168,7 +168,6 @@ proc myou_main_loop*(self: MyouEngine) =
     ##
     ## You usually don't need to call this. Use `run <#run,MyouEngine>`_
     ## instead.
-    self.renderer.unbind_all_ubos()
     when compileOption("threads"):
         updateTextureWorkerThreads()
         updateLoadableWorkerThreads()
diff --git a/src/objects/gameobject.nim b/src/objects/gameobject.nim
index 9d4134e..00b0952 100644
--- a/src/objects/gameobject.nim
+++ b/src/objects/gameobject.nim
@@ -486,6 +486,9 @@ proc remove*(self: GameObject, recursive: bool = true) =
         self.scene.remove_object(self, recursive)
 
 proc destroy*(self: GameObject, recursive: bool = true) =
+    if self.is_mesh and self.get_mesh.data.nonNil:
+        self.get_mesh.data.gpu_buffers_delete()
+        self.get_mesh.materials.setLen 0
     self.body.destroy()
     self.remove(recursive)
     if recursive:
@@ -494,7 +497,9 @@ proc destroy*(self: GameObject, recursive: bool = true) =
             child.destroy(true)
     self.engine.objects.del(self.name)
     self.object_render_ubo.unbind()
+    self.object_render_ubo.destroy()
     self.object_ubo.unbind()
+    self.object_ubo.destroy()
 
 proc convert_bone_child_to_bone_parent*(self: GameObject) =
     assert self.parent == nil or self.parent.is_armature, "An armature parent is required"
diff --git a/src/objects/light.nim b/src/objects/light.nim
index 6d89c32..e69e202 100644
--- a/src/objects/light.nim
+++ b/src/objects/light.nim
@@ -136,8 +136,6 @@ proc configure_shadow*(self: Light,
         for ob in self.scene.children:
             if not (ob.is_mesh and ob.visible):
                 continue
-            echo "adding ", ob.name, " otype ", ob.otype
-            # discard ob.get_world_matrix
             let me = ob.get_mesh
             let bb = me.bound_box
             let world_dim = (ob.world_matrix * vec4(bb[1] - bb[0], 0.0)).xyz
diff --git a/src/objects/mesh.nim b/src/objects/mesh.nim
index 6d0ab7d..1cc3049 100644
--- a/src/objects/mesh.nim
+++ b/src/objects/mesh.nim
@@ -91,23 +91,14 @@ proc remove*(self: MeshData, ob: Mesh, delete_buffers: bool = true) =
         self.users.delete(idx)
         idx = self.users.find(ob)
     if self.users.len == 0:
-        # if delete_buffers:
-        #     glBindBuffer(GL_ARRAY_BUFFER, 0)
-        #     for buf in self.vertex_buffers:
-        #         glDeleteBuffers(1, addr buf)
-        #     for buf in self.index_buffers:
-        #         glDeleteBuffers(1, addr buf)
-        #     glBindVertexArray(0)
-        #     for vao in self.vaos:
-        #         glDeleteVertexArrays(1, addr vao)
         self.engine.mesh_datas.del(self.hash)
     ob.data = nil
 
 proc write_vaos*(self: MeshData) =
     for i,vao in self.vaos:
-        if vao == 0:
+        if vao.int == 0:
             continue
-        glBindVertexArray(vao)
+        glBindVertexArray(vao.GLuint)
         for vb_attrs in self.vao_specs[i].vbs.mitems:
             glBindBuffer(GL_ARRAY_BUFFER, vb_attrs.vb)
             for a in vb_attrs.attribs:
@@ -117,7 +108,7 @@ proc write_vaos*(self: MeshData) =
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.vao_specs[i].ib)
         when defined(myouUseRenderdoc):
             let name = &"{self.name} {i}"
-            glObjectLabel(GL_VERTEX_ARRAY, vao, GLsizei(name.len), name.cstring)
+            glObjectLabel(GL_VERTEX_ARRAY, vao.GLuint, GLsizei(name.len), name.cstring)
         glBindVertexArray(0)
 
 proc gpu_buffers_upload*(self: MeshData) =
@@ -130,9 +121,9 @@ proc gpu_buffers_upload*(self: MeshData) =
     for idx,va in self.varrays:
         if va.len == 0:
             self.num_indices.add(0)
-            self.vertex_buffers.add(0)
-            self.index_buffers.add(0)
-            self.vaos.add(0)
+            self.vertex_buffers.add(0.GPUBuffer)
+            self.index_buffers.add(0.GPUBuffer)
+            self.vaos.add(0.GPUVao)
             self.vao_specs.add VaoSpec()
             continue
         var vb: GLuint
@@ -143,7 +134,7 @@ proc gpu_buffers_upload*(self: MeshData) =
         # TODO: initialize without uploading when we know that the array is just zeroes
         glBufferData(GL_ARRAY_BUFFER, buffer_size.GLsizeiptr, addr va[0], GL_DYNAMIC_DRAW)
         glBindBuffer(GL_ARRAY_BUFFER, 0)
-        self.vertex_buffers.add(vb)
+        self.vertex_buffers.add(vb.GPUBuffer)
         var ib: GLuint = 0
         var num_indices: Natural
         if idx < self.iarrays.len:
@@ -167,7 +158,7 @@ proc gpu_buffers_upload*(self: MeshData) =
                 self.num_indices.add(num_indices.int32)
         elif not had_indices:
             self.num_indices.add((buffer_size div self.stride).int32)
-        self.index_buffers.add(ib)
+        self.index_buffers.add(ib.GPUBuffer)
         if self.use_tf:
             self.tf_vbos.setLen 2
             glGenBuffers(2, addr tf[0])
@@ -180,8 +171,8 @@ proc gpu_buffers_upload*(self: MeshData) =
             glBindBuffer(GL_ARRAY_BUFFER, tf[1])
             glBufferData(GL_ARRAY_BUFFER, tf_buffer_size.GLsizeiptr, nil, GL_DYNAMIC_DRAW)
             glBindBuffer(GL_ARRAY_BUFFER, 0)
-            self.tf_vbos[idx].add tf[0]
-            self.tf_vbos[idx].add tf[1]
+            self.tf_vbos[idx].add tf[0].GPUBuffer
+            self.tf_vbos[idx].add tf[1].GPUBuffer
         # If transform feedback is enabled, we create two VAOs that have two
         # parts:
         # * The regular mesh, which has the same buffers and attributes in each
@@ -203,7 +194,7 @@ proc gpu_buffers_upload*(self: MeshData) =
         )
         var vao: GLuint
         glGenVertexArrays(1, addr vao)
-        self.vaos.add(vao)
+        self.vaos.add(vao.GPUVao)
         if self.use_tf:
             var vao_tf = vao_spec
             vao_spec.vbs.add VertexBufferAttribs(vb: tf[0], attribs: self.tf_layout)
@@ -218,14 +209,15 @@ proc gpu_buffers_upload*(self: MeshData) =
     # set loaded to true after that
 
 proc gpu_buffers_delete*(self: MeshData) =
+    glBindVertexArray(0)
+    self.vaos = @[]
+    self.tf_vaos = @[]
+    self.vao_specs = @[]
+    self.tf_vao_specs = @[]
+    glBindBuffer(GL_ARRAY_BUFFER, 0)
     self.vertex_buffers = @[]
     self.index_buffers = @[]
     self.loaded = false
-    glBindVertexArray(0)
-    for i in 0 ..< self.vaos.len:
-        glDeleteVertexArrays(1, addr self.vaos[i])
-    # TODO! delete individual buffers?
-    self.vaos = @[]
     if self.users.len == 0:
         self.engine.mesh_datas.del(self.hash)
 
@@ -233,14 +225,14 @@ proc update_varray*(self: MeshData) =
     if self.vertex_buffers.len == 0:
         return
     for i,va in self.varrays:
-        glBindBuffer(GL_ARRAY_BUFFER, self.vertex_buffers[i])
+        glBindBuffer(GL_ARRAY_BUFFER, self.vertex_buffers[i].GLuint)
         glBufferSubData(GL_ARRAY_BUFFER, 0.GLintptr, cast[GLsizeiptr](va.bytelen), addr va[0])
 
 proc update_iarray*(self: MeshData) =
     if self.index_buffers.len == 0:
         return
     for i,ia in self.iarrays:
-        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.index_buffers[i])
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, self.index_buffers[i].GLuint)
         glBufferData(GL_ELEMENT_ARRAY_BUFFER, cast[GLsizeiptr](ia.bytelen), addr ia[0], GL_STATIC_DRAW)
 
 proc clone*(self: MeshData): MeshData =
diff --git a/src/platform/gl.nim b/src/platform/gl.nim
index 88ff6b7..8de3247 100644
--- a/src/platform/gl.nim
+++ b/src/platform/gl.nim
@@ -20,4 +20,49 @@ proc get_program_info_log*(program: GLuint): string =
     glGetProgramInfoLog(program, logSize.GLsizei, nil, s.cstring)
     return s
 
+let main_thread_id = getThreadID()
+
+template handleError(x: untyped, t: string) =
+    assert main_thread_id == getThreadID()
+    try:
+        x
+    except:
+        echo "Error when deleting " & t
+        echo getCurrentExceptionMsg()
+
+type GPUBuffer* = distinct GLuint
+type GPUTexture* = distinct GLuint
+type GPUVao* = distinct GLuint
+type GPUFramebuffer* = distinct GLuint
+type GPURenderbuffer* = distinct GLuint
+type GPUProgram* = distinct GLuint
+type GPUShader* = distinct GLuint
+
+proc `=destroy`(x: var GPUBuffer) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteBuffers(1, x.GLuint.addr), "Buffer"
+
+proc `=destroy`(x: var GPUTexture) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteTextures(1, x.GLuint.addr), "Texture"
+
+proc `=destroy`(x: var GPUVao) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteVertexArrays(1, x.GLuint.addr), "VertexArray"
+
+proc `=destroy`(x: var GPUFramebuffer) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteFramebuffers(1, x.GLuint.addr), "Framebuffer"
+
+proc `=destroy`(x: var GPURenderbuffer) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteRenderbuffers(1, x.GLuint.addr), "Renderbuffer"
+
+proc `=destroy`(x: var GPUProgram) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteProgram(x.GLuint), "Program"
+
+proc `=destroy`(x: var GPUShader) =
+    if x.GLuint != 0.GLuint:
+        handleError glDeleteShader(x.GLuint), "Shader"
 
diff --git a/src/scene.nim b/src/scene.nim
index ef66bb4..81104dd 100644
--- a/src/scene.nim
+++ b/src/scene.nim
@@ -343,7 +343,6 @@ proc set_objects_auto_update_matrix*(self: Scene, objects: seq[GameObject], auto
 
 proc destroy*(self: Scene) =
     for ob in reversed(self.children):
-        var ob = ob
         ob.destroy(recursive=false)
     self.world.destroy()
     for mat in self.materials.values:
@@ -353,6 +352,17 @@ proc destroy*(self: Scene) =
     for ubo in self.lighting_UBOs:
         ubo.destroy()
     self.engine.scenes.del(self.name)
+    # bound textures can linger
+    unbindAllTextures()
+    # probably none of this is actually necessary
+    # (needs testing without this)
+    self.children = @[]
+    self.auto_updated_children = @[]
+    self.objects.clear()
+    self.parents.clear()
+    self.materials.clear()
+    self.textures.clear()
+    self.mesh_passes = @[]
 
 proc enable_render*(self: Scene) =
     self.enabled = true
@@ -417,9 +427,9 @@ proc calculate_max_lights_and_cubemaps*(self: Scene) =
     for _,mat in self.materials:
         if mat.ubos.anyIt it in self.lighting_UBOs:
             mat.delete_all_shaders
-    echo &"calculated max lights {self.max_point_lights} {self.max_sun_lights}"
-    echo &"calculated max shadow maps {self.max_shadow_maps}"
-    echo &"calculated max cubemaps {self.max_cubemaps}"
+    # echo &"calculated max lights {self.max_point_lights} {self.max_sun_lights}"
+    # echo &"calculated max shadow maps {self.max_shadow_maps}"
+    # echo &"calculated max cubemaps {self.max_cubemaps}"
 
 proc get_lighting_UBOs*(self: Scene): seq[UBO] =
     # echo &"getting UBOs {self.max_point_lights} {self.max_sun_lights}"
@@ -620,7 +630,7 @@ proc sort_cubemaps*(self: Scene) =
 #       or share depth buffers?
 
 proc ensure_cubemaps*(self: Scene) =
-    echo "ensuring cubemaps"
+    # echo "ensuring cubemaps"
     let res = self.cubemap_resolution
     if res == 0:
         return
@@ -650,7 +660,7 @@ proc ensure_cubemaps*(self: Scene) =
             )
         probe.ubo_index = self.cubemaps.len.int32
         self.cubemaps.add(probe.cubemap)
-    echo &"made {self.cubemaps.len} cubemaps"
+    # echo &"made {self.cubemaps.len} cubemaps"
 
 proc render_all_cubemaps*(self: Scene, use_roughness_prefiltering: bool, mipmap_shader: Material = nil) =
     if self.cubemap_UBO == nil:
diff --git a/src/types.nim b/src/types.nim
index 53436fb..3349a89 100644
--- a/src/types.nim
+++ b/src/types.nim
@@ -167,11 +167,11 @@ type
         varrays*: seq[ArrRef[float32]]
         iarrays*: seq[ArrRef[uint16]]
         loaded*: bool
-        vertex_buffers*: seq[GLuint] ## private
+        vertex_buffers*: seq[GPUBuffer] ## private
         vertex_starts*: seq[int32] ## private
-        index_buffers*: seq[GLuint] ## private
+        index_buffers*: seq[GPUBuffer] ## private
         num_indices*: seq[int32] ## private
-        vaos*: seq[GLuint] ## private
+        vaos*: seq[GPUVao] ## private
         vao_specs*: seq[VaoSpec] ## private
         index_types*: seq[DataType] ## private
         layout*: AttributeList ## private
@@ -183,8 +183,8 @@ type
         # load_promise: unknown
         # load_resolve: unknown
         use_tf*: bool ## private
-        tf_vbos*: seq[seq[GLuint]] ## private
-        tf_vaos*: seq[GLuint] ## private
+        tf_vbos*: seq[seq[GPUBuffer]] ## private
+        tf_vaos*: seq[GPUVao] ## private
         tf_vao_specs*: seq[VaoSpec] ## private
         tf_layout*: AttributeList ## private
         when defined(myouUseRenderdoc):
@@ -504,7 +504,7 @@ type
         name*: string
         size32*: int
         byte_storage*: ArrRef[byte]
-        buffer*: GLuint
+        buffer*: GPUBuffer
         binding_point*: int32
         # needs_update*: bool
 
@@ -555,14 +555,14 @@ type
         defines*: Table[string, string]
 
         ###
-        scene*: Scene
+        scene* {.cursor.}: Scene
         shaders*: Table[AttributeList, Shader] ## private
         users*: seq[GameObject] ## private
-        render_scene*: Scene ## private
+        render_scene* {.cursor.}: Scene ## private
         has_texture_list_checked*: bool ## private
         shader_library*: string ## private
         use_debug_shaders*: bool ## private
-        last_shader*: Shader ## private
+        last_shader* {.cursor.}: Shader ## private
 
         feedback_varyings*: seq[string]
     
@@ -570,8 +570,8 @@ type
     Shader* = ref object
         engine* {.cursor.}: MyouEngine # do we need this?
         id*: int
-        program*: GLuint
-        material*: Material # do we need this?
+        program*: GPUProgram
+        material* {.cursor.}: Material # do we need this?
 
         # TODO: combine in single seq?
         ubos*: seq[UBO]
@@ -638,7 +638,7 @@ type
     TextureStorage* = ref object ## private
         unit*: GLint
         target*: GLenum
-        tex*: GLuint
+        tex*: GPUTexture
         iformat*: GLenum
         format*, gltype*: GLenum
         # index of the first layer (or only layer if not using tiles)
@@ -651,7 +651,7 @@ type
         name*: string
         storage*: TextureStorage ## private
         loaded*: bool
-        last_used_shader*: Shader ## private
+        last_used_shader* {.cursor.}: Shader ## private
         sampler_object*: GLuint ## private
         width*, height*, depth*: int
         tex_type*: TextureType
@@ -915,4 +915,5 @@ template enqueue*(renderer: RenderManager, fun: untyped) =
 
 when not defined(release):
     from sugar import dump
-    export sugar
+    export sugar.dump
+