From 608f81e6c2220fe2dc01c8c903ccc3706243dcd3 Mon Sep 17 00:00:00 2001
From: Stephan Unverwerth <s.unverwerth@gmx.de>
Date: Sat, 8 May 2021 22:18:34 +0200
Subject: [PATCH] LibGL: Add depth buffer class

---
 Userland/Libraries/LibGL/CMakeLists.txt  |  1 +
 Userland/Libraries/LibGL/DepthBuffer.cpp | 36 ++++++++++++++++++++++++
 Userland/Libraries/LibGL/DepthBuffer.h   | 27 ++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 Userland/Libraries/LibGL/DepthBuffer.cpp
 create mode 100644 Userland/Libraries/LibGL/DepthBuffer.h

diff --git a/Userland/Libraries/LibGL/CMakeLists.txt b/Userland/Libraries/LibGL/CMakeLists.txt
index 0c77e123c0..637658c73d 100644
--- a/Userland/Libraries/LibGL/CMakeLists.txt
+++ b/Userland/Libraries/LibGL/CMakeLists.txt
@@ -7,6 +7,7 @@ set(SOURCES
     GLVert.cpp
     SoftwareGLContext.cpp
     SoftwareRasterizer.cpp
+    DepthBuffer.cpp
 )
 
 serenity_lib(LibGL gl)
diff --git a/Userland/Libraries/LibGL/DepthBuffer.cpp b/Userland/Libraries/LibGL/DepthBuffer.cpp
new file mode 100644
index 0000000000..431b043354
--- /dev/null
+++ b/Userland/Libraries/LibGL/DepthBuffer.cpp
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "DepthBuffer.h"
+
+namespace GL {
+
+DepthBuffer::DepthBuffer(Gfx::IntSize const& size)
+    : m_size(size)
+    , m_data(new float[size.width() * size.height()])
+{
+}
+
+DepthBuffer::~DepthBuffer()
+{
+    delete[] m_data;
+}
+
+float* DepthBuffer::scanline(int y)
+{
+    VERIFY(y >= 0 && y < m_size.height());
+    return &m_data[y * m_size.width()];
+}
+
+void DepthBuffer::clear(float depth)
+{
+    int num_entries = m_size.width() * m_size.height();
+    for (int i = 0; i < num_entries; ++i) {
+        m_data[i] = depth;
+    }
+}
+
+}
diff --git a/Userland/Libraries/LibGL/DepthBuffer.h b/Userland/Libraries/LibGL/DepthBuffer.h
new file mode 100644
index 0000000000..7f78d19248
--- /dev/null
+++ b/Userland/Libraries/LibGL/DepthBuffer.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGfx/Size.h>
+
+namespace GL {
+
+class DepthBuffer final {
+public:
+    DepthBuffer(Gfx::IntSize const&);
+    ~DepthBuffer();
+
+    float* scanline(int y);
+
+    void clear(float depth);
+
+private:
+    Gfx::IntSize m_size;
+    float* m_data { nullptr };
+};
+
+}