Reimplement Vulkan shader objects. (#1764)

* Reimplement Vulkan shader objects.

This change reimplements Vulkan shader objects in the `gfx` layer so that it is no longer layered on top of the `DescriptorSet` abstraction. Since this is the last implementation that uses `DescriptorSet`, the change also removes all `DescriptorSet` related API from public `gfx` interface.

The Vulkan implementation now passes all test cases, but it still have two issues:
1. The PushConstant setting is not correct, this is because we don't seem to be able to get correct reflection data about the size of push constants for an entry-point.
2. The `shader-toy` example can't run on Vulkan, because it currently sets nullptr to `Texture` bindings, and this change doesn't properly handle setting resource to null in `ShaderObject`s yet. If we can use the `nullDescriptor` feature on vulkan, this implementation will be simple. However we still want to decide whether we want to use a Vulkan 1.2 feature for this.

* Fix up

1 files changed, 0 insertions, 17 deletions

diff --git a/tools/gfx/command-writer.h b/tools/gfx/command-writer.h
index 8aba454f4..76a72edc3 100644
--- a/tools/gfx/command-writer.h
+++ b/tools/gfx/command-writer.h
@@ -10,7 +10,6 @@ namespace gfx
 enum class CommandName
 {
     SetPipelineState,
-    SetDescriptorSet,
     BindRootShaderObject,
     SetFramebuffer,
     ClearFrame,
@@ -128,22 +127,6 @@ public:
         m_commands.add(Command(CommandName::SetPipelineState, offset));
     }
 
-    void setDescriptorSet(
-        PipelineType pipelineType,
-        IPipelineLayout* layout,
-        UInt index,
-        IDescriptorSet* descriptorSet)
-    {
-        uint32_t pipelineLayoutOffset = encodeObject(layout);
-        uint32_t descSetOffset = encodeObject(descriptorSet);
-        m_commands.add(Command(
-            CommandName::SetDescriptorSet,
-            (uint32_t)pipelineType,
-            pipelineLayoutOffset,
-            (uint32_t)index,
-            descSetOffset));
-    }
-
     void bindRootShaderObject(PipelineType pipelineType, IShaderObject* object)
     {
         auto rootOffset = encodeObject(object);