From 7b1268d4a4ddd381360d8d51b3d5cb5629e78fc2 Mon Sep 17 00:00:00 2001
From: Vitor Fernandes <vitor.fernandes@jumo.world>
Date: Sat, 20 Jun 2020 15:46:40 +0100
Subject: [PATCH] Abstraction over layouts

---
 src/opengl/CMakeLists.txt       |  1 +
 src/opengl/VertexArray.cpp      | 36 ++++++++++++++++
 src/opengl/VertexArray.h        | 18 ++++++++
 src/opengl/VertexBufferLayout.h | 73 +++++++++++++++++++++++++++++++++
 src/opengl/gl1.cpp              | 17 ++++----
 5 files changed, 137 insertions(+), 8 deletions(-)
 create mode 100644 src/opengl/VertexArray.cpp
 create mode 100644 src/opengl/VertexArray.h
 create mode 100644 src/opengl/VertexBufferLayout.h

diff --git a/src/opengl/CMakeLists.txt b/src/opengl/CMakeLists.txt
index 0225057..0bc85a5 100644
--- a/src/opengl/CMakeLists.txt
+++ b/src/opengl/CMakeLists.txt
@@ -13,6 +13,7 @@ add_executable(
   Renderer.cpp
   VertexBuffer.cpp
   IndexBuffer.cpp
+  VertexArray.cpp
   glew.c
 )
 
diff --git a/src/opengl/VertexArray.cpp b/src/opengl/VertexArray.cpp
new file mode 100644
index 0000000..b290398
--- /dev/null
+++ b/src/opengl/VertexArray.cpp
@@ -0,0 +1,36 @@
+#include "VertexArray.h"
+#include "Renderer.h"
+
+VertexArray::VertexArray()
+{
+  GLCall(glGenVertexArrays(1,&m_RendererID));
+}
+
+VertexArray::~VertexArray()
+{
+  GLCall(glDeleteVertexArrays(1,&m_RendererID));
+}
+
+void VertexArray::AddBuffer(const VertexBuffer &vb, const VertexBufferLayout& layout)
+{
+  vb.Bind();
+  const auto &elements = layout.GetElements();
+  unsigned int offset=0;
+  for (unsigned int i = 0; i < elements.size(); i++)
+  {
+    const auto &element = elements[i];
+    GLCall(glEnableVertexAttribArray(i));
+    GLCall(glVertexAttribPointer(i, elements[i].count, element.type,element.normalized, layout.GetStride(), (const void*)offset));
+    offset+=element.count * VertexBufferElement::GetSizeOfType(element.type); 
+  }
+}
+
+void VertexArray::Bind() const
+{
+  GLCall(glBindVertexArray(m_RendererID));
+}
+
+void VertexArray::Unbind() const
+{
+  GLCall(glBindVertexArray(0));
+}
\ No newline at end of file
diff --git a/src/opengl/VertexArray.h b/src/opengl/VertexArray.h
new file mode 100644
index 0000000..59fa586
--- /dev/null
+++ b/src/opengl/VertexArray.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "VertexBuffer.h"
+#include "VertexBufferLayout.h"
+
+class VertexArray
+{
+private:
+  unsigned int m_RendererID;
+
+public:
+  VertexArray();
+  ~VertexArray();
+
+  void AddBuffer(const VertexBuffer &vb, const VertexBufferLayout &layout);
+  void Bind() const;
+  void Unbind() const;
+};
\ No newline at end of file
diff --git a/src/opengl/VertexBufferLayout.h b/src/opengl/VertexBufferLayout.h
new file mode 100644
index 0000000..7c38c43
--- /dev/null
+++ b/src/opengl/VertexBufferLayout.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <vector>
+#include "glew.h"
+#include "Renderer.h"
+
+struct VertexBufferElement
+{
+  unsigned int type;
+  unsigned int count;
+  unsigned char normalized;
+  static unsigned int GetSizeOfType(unsigned int type)
+  {
+    switch (type)
+    {
+    case GL_FLOAT:
+      return 4;
+    case GL_UNSIGNED_INT:
+      return 4;
+    case GL_UNSIGNED_BYTE:
+      return 1;
+    }
+    ASSERT(false);
+    return 0;
+  };
+};
+
+class VertexBufferLayout
+{
+private:
+  std::vector<VertexBufferElement> m_Elements;
+  unsigned int m_Stride;
+
+public:
+  VertexBufferLayout() : m_Stride(0)
+  {
+  }
+
+  template <typename T>
+  void Push(unsigned count);
+  template <>
+  void Push<float>(unsigned int count)
+  {
+    VertexBufferElement vbe = {GL_FLOAT, count, GL_FALSE};
+    m_Elements.push_back(vbe);
+    m_Stride += count * VertexBufferElement::GetSizeOfType(GL_FLOAT);
+  };
+
+  template <>
+  void Push<unsigned int>(unsigned int count)
+  {
+    VertexBufferElement vbe = {GL_UNSIGNED_INT, count, GL_FALSE};
+    m_Elements.push_back(vbe);
+    m_Stride += count * VertexBufferElement::GetSizeOfType(GL_UNSIGNED_INT);
+  }
+
+  template <>
+  void Push<unsigned char>(unsigned int count)
+  {
+    VertexBufferElement vbe = {GL_UNSIGNED_BYTE, count, GL_TRUE};
+    m_Elements.push_back(vbe);
+    m_Stride += count * VertexBufferElement::GetSizeOfType(GL_UNSIGNED_BYTE);
+  }
+
+  inline const std::vector<VertexBufferElement> GetElements() const &
+  {
+    return m_Elements;
+  }
+  inline unsigned int GetStride() const
+  {
+    return m_Stride;
+  }
+};
\ No newline at end of file
diff --git a/src/opengl/gl1.cpp b/src/opengl/gl1.cpp
index 0cc7233..1b29b70 100644
--- a/src/opengl/gl1.cpp
+++ b/src/opengl/gl1.cpp
@@ -7,6 +7,7 @@
 #include "Renderer.h"
 #include "VertexBuffer.h"
 #include "IndexBuffer.h"
+#include "VertexArray.h"
 
 typedef unsigned int uint;
 
@@ -141,11 +142,14 @@ int main(void)
 
     //Create buffer
     //Buffer id
-    VertexBuffer* vb = new VertexBuffer(positions, 4 * 2 * sizeof(float));
-    GLCall(glEnableVertexAttribArray(0));
-    GLCall(glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0));
+    VertexArray va ;
+    VertexBuffer vb(positions, 4 * 2 * sizeof(float));
+    
+    VertexBufferLayout layout;
+    layout.Push<float>(2);
+    va.AddBuffer(vb,layout);
 
-    IndexBuffer* ib = new IndexBuffer(indexes,6);
+    IndexBuffer ib(indexes,6);
     ShaderProgramSource source = ParseShader(SHADERS_PATH);
 
     uint shader = CreateShader(source.VertexSource, source.FragmentSource);
@@ -183,8 +187,7 @@ int main(void)
 
         GLCall(glUniform4f(uniform_location, 0.2f, 0.3f, 0.8f, 1.0f));
 
-        //GLCall(glBindVertexArray(vb));
-        ib->Bind();
+        ib.Bind();
 
         GLCall(glDrawElements(GL_TRIANGLES, 6 * sizeof(uint), GL_UNSIGNED_INT, nullptr));
 
@@ -202,8 +205,6 @@ int main(void)
         glfwPollEvents();
     }
 
-    delete ib;
-    delete vb;
     glfwTerminate();
     return 0;
 }
\ No newline at end of file