Add support for instanced draws

Adds an instance buffer to GrMesh and instance attribs to
GrPrimitiveProcessor. Implements support in GL and Vulkan. Adds unit
tests for instanced rendering with GrMesh.

Bug: skia:
Change-Id: If1a9920feb9366f346b8c37cf914713c49129b3a
Reviewed-on: https://skia-review.googlesource.com/16200
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/gpu/gl/GrGLVertexArray.h b/src/gpu/gl/GrGLVertexArray.h
index 1970e30425..553df4f3fd 100644
--- a/src/gpu/gl/GrGLVertexArray.h
+++ b/src/gpu/gl/GrGLVertexArray.h
@@ -42,7 +42,8 @@ public:
              const GrBuffer* vertexBuffer,
              GrVertexAttribType type,
              GrGLsizei stride,
-             size_t offsetInBytes);
+             size_t offsetInBytes,
+             int divisor = 0);
 
     /**
      * This function enables the first 'enabledCount' vertex arrays and disables the rest.
@@ -63,16 +64,22 @@ public:
     int count() const { return fAttribArrayStates.count(); }
 
 private:
+    static constexpr int kInvalidDivisor = -1;
+
     /**
      * Tracks the state of glVertexAttribArray for an attribute index.
      */
     struct AttribArrayState {
-        void invalidate() { fVertexBufferUniqueID.makeInvalid(); }
+        void invalidate() {
+            fVertexBufferUniqueID.makeInvalid();
+            fDivisor = kInvalidDivisor;
+        }
 
         GrGpuResource::UniqueID   fVertexBufferUniqueID;
         GrVertexAttribType        fType;
         GrGLsizei                 fStride;
         size_t                    fOffset;
+        int                       fDivisor;
     };
 
     SkSTArray<16, AttribArrayState, true>   fAttribArrayStates;