diff --git a/Cargo.lock b/Cargo.lock
index 9f950e4a5..662d5200e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -660,7 +660,7 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -681,7 +681,7 @@ name = "rand_hc"
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -719,7 +719,7 @@ name = "rand_xorshift"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
diff --git a/wgpu-native/src/command/render.rs b/wgpu-native/src/command/render.rs
index 32b8e97a0..f00dfe4d4 100644
--- a/wgpu-native/src/command/render.rs
+++ b/wgpu-native/src/command/render.rs
@@ -1,6 +1,10 @@
+use crate::resource::BufferUsageFlags;
 use crate::registry::{Items, HUB};
-use crate::track::{BufferTracker, TextureTracker};
-use crate::{CommandBuffer, CommandBufferId, RenderPassId, Stored};
+use crate::track::{BufferTracker, TextureTracker, TrackPermit};
+use crate::{
+    CommandBuffer, Stored,
+    BufferId, CommandBufferId, RenderPassId,
+};
 
 use hal::command::RawCommandBuffer;
 
@@ -47,3 +51,63 @@ pub extern "C" fn wgpu_render_pass_end_pass(pass_id: RenderPassId) -> CommandBuf
     cmb.raw.push(pass.raw);
     pass.cmb_id.value
 }
+
+#[no_mangle]
+pub extern "C" fn wgpu_render_pass_set_index_buffer(
+    pass_id: RenderPassId, buffer_id: BufferId, offset: u32
+) {
+    let mut pass_guard = HUB.render_passes.write();
+    let buffer_guard = HUB.buffers.read();
+
+    let pass = pass_guard.get_mut(pass_id);
+    let buffer = buffer_guard.get(buffer_id);
+    pass.buffer_tracker
+        .transit(
+            buffer_id,
+            &buffer.life_guard.ref_count,
+            BufferUsageFlags::INDEX,
+            TrackPermit::EXTEND,
+        )
+        .unwrap();
+
+    let view = hal::buffer::IndexBufferView {
+        buffer: &buffer.raw,
+        offset: offset as u64,
+        index_type: hal::IndexType::U16, //TODO?
+    };
+
+    unsafe {
+        pass.raw.bind_index_buffer(view);
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn wgpu_render_pass_set_vertex_buffers(
+    pass_id: RenderPassId, buffers: &[BufferId], offsets: &[u32]
+) {
+    let mut pass_guard = HUB.render_passes.write();
+    let buffer_guard = HUB.buffers.read();
+
+    let pass = pass_guard.get_mut(pass_id);
+    for &id in buffers {
+        let buffer = buffer_guard.get(id);
+        pass.buffer_tracker
+            .transit(
+                id,
+                &buffer.life_guard.ref_count,
+                BufferUsageFlags::VERTEX,
+                TrackPermit::EXTEND,
+            )
+            .unwrap();
+    }
+
+    assert_eq!(buffers.len(), offsets.len());
+    let buffers = buffers
+        .iter()
+        .map(|&id| &buffer_guard.get(id).raw)
+        .zip(offsets.iter().map(|&off| off as u64));
+
+    unsafe {
+        pass.raw.bind_vertex_buffers(0, buffers);
+    }
+}
diff --git a/wgpu-native/src/track.rs b/wgpu-native/src/track.rs
index 767fa3978..087551641 100644
--- a/wgpu-native/src/track.rs
+++ b/wgpu-native/src/track.rs
@@ -26,7 +26,12 @@ pub struct Query<T> {
 
 bitflags! {
     pub struct TrackPermit: u32 {
+        /// Allow extension of the current usage. This is useful during render pass
+        /// recording, where the usage has to stay constant, but we can defer the
+        /// decision on what it is until the end of the pass.
         const EXTEND = 1;
+        /// Allow replacing the current usage with the new one. This is useful when
+        /// recording a command buffer live, and the current usage is already been set.
         const REPLACE = 2;
     }
 }