LibGL: Add depth buffer class

Author: https://github.com/sunverwerth
Commit: https://github.com/SerenityOS/serenity/commit/608f81e6c22
Pull-request: https://github.com/SerenityOS/serenity/pull/6973

Userland/Libraries/LibGL/CMakeLists.txt

@@ -7,6 +7,7 @@ set(SOURCES
     GLVert.cpp
     SoftwareGLContext.cpp
     SoftwareRasterizer.cpp
+    DepthBuffer.cpp
 )
 
 serenity_lib(LibGL gl)

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;
+    }
+}
+
+}

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 };
+};
+
+}