Add resource types to CommandBuffer

This is a little ugly, but it allows us to have access to the resource types without CommandBuffer needing to have access to Device, which would result in a rustc stack overflow.

src/device/draw.rs

@@ -77,6 +77,14 @@ impl DataBuffer {
 /// An interface of the abstract command buffer. It collects commands in an
 /// efficient API-specific manner, to be ready for execution on the device.
 pub trait CommandBuffer {
+    type Buffer;
+    type ArrayBuffer;
+    type Program;
+    type FrameBuffer;
+    type Surface;
+    type Texture;
+    type Sampler;
+
     /// An empty constructor
     fn new() -> Self;
     /// Clear the command buffer contents, retain the allocated storage

src/device/gl_device/draw.rs

@@ -18,7 +18,7 @@ use std::slice;
 
 use {attrib, draw, target, tex, shade, state};
 use {AttributeSlot, IndexType, InstanceCount, PrimitiveType, TextureSlot, UniformBlockIndex, UniformBufferSlot, VertexCount};
-use super::{ArrayBuffer, Buffer, FrameBuffer, Program, Surface, Texture};
+use super::{ArrayBuffer, Buffer, FrameBuffer, Program, Sampler, Surface, Texture};
 
 /// Serialized device command.
 #[derive(Copy, Debug)]
@@ -62,6 +62,14 @@ impl CommandBuffer {
 }
 
 impl draw::CommandBuffer for CommandBuffer {
+    type Buffer         = Buffer;
+    type ArrayBuffer    = ArrayBuffer;
+    type Program        = Program;
+    type FrameBuffer    = FrameBuffer;
+    type Surface        = Surface;
+    type Texture        = Texture;
+    type Sampler        = Sampler;
+
     fn new() -> CommandBuffer {
         CommandBuffer {
             buf: Vec::new(),

src/device/lib.rs

@@ -318,7 +318,16 @@ pub struct BufferInfo {
 /// An interface for performing draw calls using a specific graphics API
 #[allow(missing_docs)]
 pub trait Device {
-    type CommandBuffer: draw::CommandBuffer;
+    type CommandBuffer:
+        draw::CommandBuffer<
+            Buffer          = Self::Buffer,
+            ArrayBuffer     = Self::ArrayBuffer,
+            Program         = Self::Program,
+            FrameBuffer     = Self::FrameBuffer,
+            Surface         = Self::Surface,
+            Texture         = Self::Texture,
+            Sampler         = Self::Sampler,
+        >;
 
     type Buffer;
     type ArrayBuffer;