fix: encapsulate OpenGL types in VertexAttribute to eliminate raw GL API usage in tests

- Add VertexAttributeType and VertexAttributeNormalized enums in OpenGLVertexArray.h
- Add ToGLAttributeType() converter in OpenGLVertexArray.cpp
- Remove glActiveTexture() call from quad test (already handled by texture.Bind())
- Remove #include <glad/glad.h> from triangle test
- Update unit tests to use encapsulated enums

All three OpenGL integration tests (minimal, triangle, quad) pass with 0% pixel difference.

engine/include/XCEngine/RHI/OpenGL/OpenGLVertexArray.h

@@ -6,11 +6,32 @@
 namespace XCEngine {
 namespace RHI {
 
+enum class VertexAttributeType {
+    Float = 0,
+    Int,
+    UnsignedInt,
+    Short,
+    UnsignedShort,
+    Byte,
+    UnsignedByte,
+    Double,
+    HalfFloat,
+    Fixed,
+    Int2101010Rev,
+    UnsignedInt2101010Rev,
+    UnsignedInt10F11F11FRev
+};
+
+enum class VertexAttributeNormalized {
+    False = 0,
+    True
+};
+
 struct VertexAttribute {
     unsigned int index;
     int count;
-    unsigned int type;
-    bool normalized;
+    VertexAttributeType type;
+    VertexAttributeNormalized normalized;
     size_t stride;
     size_t offset;
 };

engine/src/RHI/OpenGL/OpenGLVertexArray.cpp

@@ -4,6 +4,25 @@
 namespace XCEngine {
 namespace RHI {
 
+static unsigned int ToGLAttributeType(VertexAttributeType type) {
+    switch (type) {
+        case VertexAttributeType::Float: return GL_FLOAT;
+        case VertexAttributeType::Int: return GL_INT;
+        case VertexAttributeType::UnsignedInt: return GL_UNSIGNED_INT;
+        case VertexAttributeType::Short: return GL_SHORT;
+        case VertexAttributeType::UnsignedShort: return GL_UNSIGNED_SHORT;
+        case VertexAttributeType::Byte: return GL_BYTE;
+        case VertexAttributeType::UnsignedByte: return GL_UNSIGNED_BYTE;
+        case VertexAttributeType::Double: return GL_DOUBLE;
+        case VertexAttributeType::HalfFloat: return GL_HALF_FLOAT;
+        case VertexAttributeType::Fixed: return GL_FIXED;
+        case VertexAttributeType::Int2101010Rev: return GL_INT_2_10_10_10_REV;
+        case VertexAttributeType::UnsignedInt2101010Rev: return GL_UNSIGNED_INT_2_10_10_10_REV;
+        case VertexAttributeType::UnsignedInt10F11F11FRev: return GL_UNSIGNED_INT_10F_11F_11F_REV;
+        default: return GL_FLOAT;
+    }
+}
+
 OpenGLVertexArray::OpenGLVertexArray()
     : m_vao(0)
     , m_indexBuffer(0)
@@ -24,8 +43,9 @@ void OpenGLVertexArray::AddVertexBuffer(unsigned int buffer, const VertexAttribu
     glBindVertexArray(m_vao);
     glBindBuffer(GL_ARRAY_BUFFER, buffer);
     glEnableVertexAttribArray(attribute.index);
-    glVertexAttribPointer(attribute.index, attribute.count, attribute.type, 
-        attribute.normalized ? GL_TRUE : GL_FALSE, 
+    glVertexAttribPointer(attribute.index, attribute.count, 
+        ToGLAttributeType(attribute.type),
+        attribute.normalized == VertexAttributeNormalized::True ? GL_TRUE : GL_FALSE, 
         attribute.stride, (void*)attribute.offset);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindVertexArray(0);