[core] make vertex descriptors constexpr

5 files changed, 100 insertions, 58 deletions

diff --git a/src/mbgl/gl/attribute.hpp b/src/mbgl/gl/attribute.hpp
index 95a9942381..53ba71a89f 100644
--- a/src/mbgl/gl/attribute.hpp
+++ b/src/mbgl/gl/attribute.hpp
@@ -18,29 +18,17 @@
 namespace mbgl {
 namespace gl {
 
-template <class> struct DataTypeOf;
-template <> struct DataTypeOf< int8_t>  : std::integral_constant<DataType, DataType::Byte> {};
-template <> struct DataTypeOf<uint8_t>  : std::integral_constant<DataType, DataType::UnsignedByte> {};
-template <> struct DataTypeOf< int16_t> : std::integral_constant<DataType, DataType::Short> {};
-template <> struct DataTypeOf<uint16_t> : std::integral_constant<DataType, DataType::UnsignedShort> {};
-template <> struct DataTypeOf< int32_t> : std::integral_constant<DataType, DataType::Integer> {};
-template <> struct DataTypeOf<uint32_t> : std::integral_constant<DataType, DataType::UnsignedInteger> {};
-template <> struct DataTypeOf<float>    : std::integral_constant<DataType, DataType::Float> {};
-
 class AttributeBinding {
 public:
-    DataType attributeType;
-    uint8_t attributeSize;
-    uint32_t attributeOffset;
-
+    gfx::AttributeDescriptor attribute;
+    uint8_t vertexStride;
     BufferID vertexBuffer;
-    uint32_t vertexSize;
     uint32_t vertexOffset;
 
     friend bool operator==(const AttributeBinding& lhs,
                            const AttributeBinding& rhs) {
-        return std::tie(lhs.attributeType, lhs.attributeSize, lhs.attributeOffset, lhs.vertexBuffer, lhs.vertexSize, lhs.vertexOffset)
-            == std::tie(rhs.attributeType, rhs.attributeSize, rhs.attributeOffset, rhs.vertexBuffer, rhs.vertexSize, rhs.vertexOffset);
+        return std::tie(lhs.attribute, lhs.vertexStride, lhs.vertexBuffer, lhs.vertexOffset)
+            == std::tie(rhs.attribute, rhs.vertexStride, rhs.vertexBuffer, rhs.vertexOffset);
     }
 };
 
@@ -51,21 +39,13 @@ using AttributeBindingArray = std::vector<optional<AttributeBinding>>;
         override the number of components available in the buffer for each vertex.  Thus,
         a buffer with only one float for each vertex can be bound to a `vec2` attribute
     */
-template <class AttributeType, class Vertex>
-AttributeBinding attributeBinding(const VertexBuffer<Vertex>& buffer,
-                                std::size_t attributeIndex,
-                                std::size_t attributeSize = AttributeType::Dimensions) {
-    static_assert(std::is_standard_layout<Vertex>::value, "vertex type must use standard layout");
-    assert(attributeSize >= 1);
-    assert(attributeSize <= 4);
-    assert(Vertex::attributeOffsets[attributeIndex] <= std::numeric_limits<uint32_t>::max());
-    static_assert(sizeof(Vertex) <= std::numeric_limits<uint32_t>::max(), "vertex too large");
-    return AttributeBinding {
-        DataTypeOf<typename AttributeType::ValueType>::value,
-        static_cast<uint8_t>(attributeSize),
-        static_cast<uint32_t>(Vertex::attributeOffsets[attributeIndex]),
+template <std::size_t I, typename Vertex>
+AttributeBinding attributeBinding(const VertexBuffer<Vertex>& buffer) {
+    static_assert(I < gfx::VertexDescriptorOf<Vertex>::data.count, "vertex attribute index out of range");
+    return {
+        gfx::VertexDescriptorOf<Vertex>::data.attributes[I],
+        gfx::VertexDescriptorOf<Vertex>::data.stride,
         buffer.buffer,
-        static_cast<uint32_t>(sizeof(Vertex)),
         0,
     };
 }
@@ -127,7 +107,7 @@ public:
     }
 
     static Bindings bindings(const VertexBuffer<gfx::Vertex<Types>>& buffer) {
-        return Bindings { attributeBinding<typename As::Type>(buffer, TypeIndex<As, As...>::value)... };
+        return Bindings { attributeBinding<TypeIndex<As, As...>::value>(buffer)... };
     }
 
     static Bindings offsetBindings(const Bindings& bindings, std::size_t vertexOffset) {
diff --git a/src/mbgl/gl/context.cpp b/src/mbgl/gl/context.cpp
index bcbb3ab66c..72d59737f3 100644
--- a/src/mbgl/gl/context.cpp
+++ b/src/mbgl/gl/context.cpp
@@ -17,14 +17,6 @@ using namespace platform;
 static_assert(underlying_type(ShaderType::Vertex) == GL_VERTEX_SHADER, "OpenGL type mismatch");
 static_assert(underlying_type(ShaderType::Fragment) == GL_FRAGMENT_SHADER, "OpenGL type mismatch");
 
-static_assert(underlying_type(DataType::Byte) == GL_BYTE, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::UnsignedByte) == GL_UNSIGNED_BYTE, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::Short) == GL_SHORT, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::UnsignedShort) == GL_UNSIGNED_SHORT, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::Integer) == GL_INT, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::UnsignedInteger) == GL_UNSIGNED_INT, "OpenGL type mismatch");
-static_assert(underlying_type(DataType::Float) == GL_FLOAT, "OpenGL type mismatch");
-
 #if not MBGL_USE_GLES2
 static_assert(underlying_type(RenderbufferType::RGBA) == GL_RGBA8, "OpenGL type mismatch");
 #else
diff --git a/src/mbgl/gl/types.hpp b/src/mbgl/gl/types.hpp
index 4c3033454f..22b7098100 100644
--- a/src/mbgl/gl/types.hpp
+++ b/src/mbgl/gl/types.hpp
@@ -32,16 +32,6 @@ enum class ShaderType : uint32_t {
     Fragment = 0x8B30
 };
 
-enum class DataType : uint16_t {
-    Byte = 0x1400,
-    UnsignedByte = 0x1401,
-    Short = 0x1402,
-    UnsignedShort = 0x1403,
-    Integer = 0x1404,
-    UnsignedInteger = 0x1405,
-    Float = 0x1406
-};
-
 enum class RenderbufferType : uint32_t {
     RGBA = 0x8058,
     DepthStencil = 0x88F0,
diff --git a/src/mbgl/gl/value.cpp b/src/mbgl/gl/value.cpp
index 4e56686103..b290cde50c 100644
--- a/src/mbgl/gl/value.cpp
+++ b/src/mbgl/gl/value.cpp
@@ -398,17 +398,102 @@ BindVertexArray::Type BindVertexArray::Get(const Context& context) {
 
 const optional<AttributeBinding> VertexAttribute::Default {};
 
+namespace {
+
+GLenum vertexType(const gfx::AttributeDataType type) {
+    switch (type) {
+        case gfx::AttributeDataType::Byte:
+        case gfx::AttributeDataType::Byte2:
+        case gfx::AttributeDataType::Byte3:
+        case gfx::AttributeDataType::Byte4:
+            return GL_BYTE;
+        case gfx::AttributeDataType::UByte:
+        case gfx::AttributeDataType::UByte2:
+        case gfx::AttributeDataType::UByte3:
+        case gfx::AttributeDataType::UByte4:
+            return GL_UNSIGNED_BYTE;
+        case gfx::AttributeDataType::Short:
+        case gfx::AttributeDataType::Short2:
+        case gfx::AttributeDataType::Short3:
+        case gfx::AttributeDataType::Short4:
+            return GL_SHORT;
+        case gfx::AttributeDataType::UShort:
+        case gfx::AttributeDataType::UShort2:
+        case gfx::AttributeDataType::UShort3:
+        case gfx::AttributeDataType::UShort4:
+            return GL_UNSIGNED_SHORT;
+        case gfx::AttributeDataType::Int:
+        case gfx::AttributeDataType::Int2:
+        case gfx::AttributeDataType::Int3:
+        case gfx::AttributeDataType::Int4:
+            return GL_INT;
+        case gfx::AttributeDataType::UInt:
+        case gfx::AttributeDataType::UInt2:
+        case gfx::AttributeDataType::UInt3:
+        case gfx::AttributeDataType::UInt4:
+            return GL_UNSIGNED_INT;
+        case gfx::AttributeDataType::Float:
+        case gfx::AttributeDataType::Float2:
+        case gfx::AttributeDataType::Float3:
+        case gfx::AttributeDataType::Float4:
+            return GL_FLOAT;
+        default:
+            return GL_FLOAT;
+    }
+}
+
+GLint components(const gfx::AttributeDataType type) {
+    switch (type) {
+        case gfx::AttributeDataType::Byte:
+        case gfx::AttributeDataType::UByte:
+        case gfx::AttributeDataType::Short:
+        case gfx::AttributeDataType::UShort:
+        case gfx::AttributeDataType::Int:
+        case gfx::AttributeDataType::UInt:
+        case gfx::AttributeDataType::Float:
+            return 1;
+        case gfx::AttributeDataType::Byte2:
+        case gfx::AttributeDataType::UByte2:
+        case gfx::AttributeDataType::Short2:
+        case gfx::AttributeDataType::UShort2:
+        case gfx::AttributeDataType::Int2:
+        case gfx::AttributeDataType::UInt2:
+        case gfx::AttributeDataType::Float2:
+            return 2;
+        case gfx::AttributeDataType::Byte3:
+        case gfx::AttributeDataType::UByte3:
+        case gfx::AttributeDataType::Short3:
+        case gfx::AttributeDataType::UShort3:
+        case gfx::AttributeDataType::Int3:
+        case gfx::AttributeDataType::UInt3:
+        case gfx::AttributeDataType::Float3:
+            return 3;
+        case gfx::AttributeDataType::Byte4:
+        case gfx::AttributeDataType::UByte4:
+        case gfx::AttributeDataType::Short4:
+        case gfx::AttributeDataType::UShort4:
+        case gfx::AttributeDataType::Int4:
+        case gfx::AttributeDataType::UInt4:
+        case gfx::AttributeDataType::Float4:
+            return 4;
+        default:
+            return 0;
+    }
+}
+
+} // namespace
+
 void VertexAttribute::Set(const optional<AttributeBinding>& binding, Context& context, AttributeLocation location) {
     if (binding) {
         context.vertexBuffer = binding->vertexBuffer;
         MBGL_CHECK_ERROR(glEnableVertexAttribArray(location));
         MBGL_CHECK_ERROR(glVertexAttribPointer(
             location,
-            static_cast<GLint>(binding->attributeSize),
-            static_cast<GLenum>(binding->attributeType),
+            components(binding->attribute.dataType),
+            vertexType(binding->attribute.dataType),
             static_cast<GLboolean>(false),
-            static_cast<GLsizei>(binding->vertexSize),
-            reinterpret_cast<GLvoid*>(binding->attributeOffset + (binding->vertexSize * binding->vertexOffset))));
+            static_cast<GLsizei>(binding->vertexStride),
+            reinterpret_cast<GLvoid*>(binding->attribute.offset + (binding->vertexStride * binding->vertexOffset))));
     } else {
         MBGL_CHECK_ERROR(glDisableVertexAttribArray(location));
     }
diff --git a/src/mbgl/gl/vertex_buffer.hpp b/src/mbgl/gl/vertex_buffer.hpp
index 0b62b86c12..b65e7f9a01 100644
--- a/src/mbgl/gl/vertex_buffer.hpp
+++ b/src/mbgl/gl/vertex_buffer.hpp
@@ -2,17 +2,12 @@
 
 #include <mbgl/gl/object.hpp>
 
-#include <vector>
-
 namespace mbgl {
 namespace gl {
 
 template <class V>
 class VertexBuffer {
 public:
-    using Vertex = V;
-    static constexpr std::size_t vertexSize = sizeof(Vertex);
-
     std::size_t vertexCount;
     UniqueBuffer buffer;
 };