LibSoftGPU: Generalize pixel buffers and standardize on BGRA8888

Between the OpenGL client and server, a lot of data type and color
conversion needs to happen. We are performing these conversions both in
`LibSoftGPU` and `LibGL`, which is not ideal. Additionally, some
concepts like the color, depth and stencil buffers should share their
logic but have separate implementations.

This is the first step towards generalizing our `LibSoftGPU` frame
buffer: a generalized `Typed3DBuffer` is introduced for arbitrary 3D
value storage and retrieval, and `Typed2DBuffer` wraps around it to
provide in an easy-to-use 2D pixel buffer. The color, depth and stencil
buffers are replaced by `Typed2DBuffer` and are now managed by the new
`FrameBuffer` class.

The `Image` class now uses multiple `Typed3DBuffer`s for layers and
mipmap levels. Additionally, the textures are now always stored as
BGRA8888, only converting between formats when reading or writing
pixels.

Ideally this refactor should have no functional changes, but some
graphical glitches in Grim Fandango seem to be fixed and most OpenGL
ports get an FPS boost on my machine. :^)

Userland/Libraries/LibSoftGPU/Buffer/FrameBuffer.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2022, Jelle Raaijmakers <jelle@gmta.nl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <LibGfx/Rect.h>
+#include <LibGfx/Size.h>
+#include <LibSoftGPU/Buffer/Typed2DBuffer.h>
+
+namespace SoftGPU {
+
+/*
+ * The frame buffer is a 2D buffer that consists of:
+ * - color buffer(s); (FIXME: implement multiple color buffers)
+ * - depth buffer;
+ * - stencil buffer;
+ * - accumulation buffer. (FIXME: implement accumulation buffer)
+ */
+template<typename C, typename D, typename S>
+class FrameBuffer final : public RefCounted<FrameBuffer<C, D, S>> {
+public:
+    static ErrorOr<NonnullRefPtr<FrameBuffer<C, D, S>>> try_create(Gfx::IntSize const& size)
+    {
+        Gfx::IntRect rect = { 0, 0, size.width(), size.height() };
+        auto color_buffer = TRY(Typed2DBuffer<C>::try_create(size));
+        auto depth_buffer = TRY(Typed2DBuffer<D>::try_create(size));
+        auto stencil_buffer = TRY(Typed2DBuffer<S>::try_create(size));
+        return adopt_ref(*new FrameBuffer(rect, color_buffer, depth_buffer, stencil_buffer));
+    }
+
+    NonnullRefPtr<Typed2DBuffer<C>> color_buffer() { return m_color_buffer; }
+    NonnullRefPtr<Typed2DBuffer<D>> depth_buffer() { return m_depth_buffer; }
+    NonnullRefPtr<Typed2DBuffer<S>> stencil_buffer() { return m_stencil_buffer; }
+    Gfx::IntRect rect() const { return m_rect; }
+
+private:
+    FrameBuffer(Gfx::IntRect rect, NonnullRefPtr<Typed2DBuffer<C>> color_buffer, NonnullRefPtr<Typed2DBuffer<D>> depth_buffer, NonnullRefPtr<Typed2DBuffer<S>> stencil_buffer)
+        : m_color_buffer(color_buffer)
+        , m_depth_buffer(depth_buffer)
+        , m_stencil_buffer(stencil_buffer)
+        , m_rect(rect)
+    {
+    }
+
+    NonnullRefPtr<Typed2DBuffer<C>> m_color_buffer;
+    NonnullRefPtr<Typed2DBuffer<D>> m_depth_buffer;
+    NonnullRefPtr<Typed2DBuffer<S>> m_stencil_buffer;
+    Gfx::IntRect m_rect;
+};
+
+}

Userland/Libraries/LibSoftGPU/Buffer/Typed2DBuffer.h

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2022, Jelle Raaijmakers <jelle@gmta.nl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/Try.h>
+#include <LibGfx/Bitmap.h>
+#include <LibGfx/Rect.h>
+#include <LibGfx/Size.h>
+#include <LibSoftGPU/Buffer/Typed3DBuffer.h>
+
+namespace SoftGPU {
+
+/**
+ * Typed2DBuffer<T> wraps TypedBuffer<T> and only interacts on the 2D plane with z = 0.
+ */
+template<typename T>
+class Typed2DBuffer final : public RefCounted<Typed2DBuffer<T>> {
+public:
+    static ErrorOr<NonnullRefPtr<Typed2DBuffer>> try_create(Gfx::IntSize const& size)
+    {
+        auto buffer = TRY(Typed3DBuffer<T>::try_create(size.width(), size.height(), 1));
+        return adopt_ref(*new Typed2DBuffer(buffer));
+    }
+
+    void fill(T value, Gfx::IntRect const& rect) { m_buffer->fill(value, rect.left(), rect.right(), rect.top(), rect.bottom(), 0, 0); }
+    ALWAYS_INLINE T* scanline(int y) { return m_buffer->buffer_pointer(0, y, 0); }
+    ALWAYS_INLINE T const* scanline(int y) const { return m_buffer->buffer_pointer(0, y, 0); }
+
+    void blit_from_bitmap(Gfx::Bitmap const& bitmap, Gfx::IntRect const& target) requires IsSame<T, u32>
+    {
+        VERIFY(bitmap.format() == Gfx::BitmapFormat::BGRA8888 || bitmap.format() == Gfx::BitmapFormat::BGRx8888);
+        int source_y = 0;
+        for (int y = target.top(); y <= target.bottom(); ++y) {
+            auto* buffer_scanline = scanline(y);
+            auto const* bitmap_scanline = bitmap.scanline(source_y++);
+
+            int source_x = 0;
+            for (int x = target.left(); x <= target.right(); ++x)
+                buffer_scanline[x] = bitmap_scanline[source_x++];
+        }
+    }
+
+    void blit_to_bitmap(Gfx::Bitmap& bitmap, Gfx::IntRect const& target) const requires IsSame<T, u32>
+    {
+        VERIFY(bitmap.format() == Gfx::BitmapFormat::BGRA8888 || bitmap.format() == Gfx::BitmapFormat::BGRx8888);
+        int source_y = 0;
+        for (int y = target.top(); y <= target.bottom(); ++y) {
+            auto const* buffer_scanline = scanline(source_y++);
+            auto* bitmap_scanline = bitmap.scanline(y);
+
+            int source_x = 0;
+            for (int x = target.left(); x <= target.right(); ++x)
+                bitmap_scanline[x] = buffer_scanline[source_x++];
+        }
+    }
+
+private:
+    Typed2DBuffer(NonnullRefPtr<Typed3DBuffer<T>> buffer)
+        : m_buffer(buffer)
+    {
+    }
+
+    NonnullRefPtr<Typed3DBuffer<T>> m_buffer;
+};
+
+}

Userland/Libraries/LibSoftGPU/Buffer/Typed3DBuffer.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2022, Jelle Raaijmakers <jelle@gmta.nl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/FixedArray.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/Try.h>
+
+namespace SoftGPU {
+
+/**
+ * TypedBuffer<T> is a generic 3D buffer that can be used to store
+ * values of a specific type at X, Y and Z coordinates. It is used as
+ * storage for images, and frame, depth and stencil buffers.
+ */
+template<typename T>
+class Typed3DBuffer final : public RefCounted<Typed3DBuffer<T>> {
+public:
+    static ErrorOr<NonnullRefPtr<Typed3DBuffer<T>>> try_create(int width, int height, int depth)
+    {
+        VERIFY(width > 0 && height > 0 && depth > 0);
+        auto data = TRY(FixedArray<T>::try_create(width * height * depth));
+        return adopt_ref(*new Typed3DBuffer(width, height, depth, move(data)));
+    }
+
+    ALWAYS_INLINE T* buffer_pointer(int x, int y, int z)
+    {
+        return &m_data[z * m_width * m_height + y * m_width + x];
+    }
+
+    ALWAYS_INLINE T const* buffer_pointer(int x, int y, int z) const
+    {
+        return &m_data[z * m_width * m_height + y * m_width + x];
+    }
+
+    void fill(T value, int x1, int x2, int y1, int y2, int z1, int z2)
+    {
+        for (auto z = z1; z <= z2; ++z) {
+            for (auto y = y1; y <= y2; ++y) {
+                auto* xline = buffer_pointer(0, y, z);
+                for (auto x = x1; x <= x2; ++x)
+                    xline[x] = value;
+            }
+        }
+    }
+
+    int depth() const { return m_depth; }
+    int height() const { return m_height; }
+    int width() const { return m_width; }
+
+private:
+    Typed3DBuffer(int width, int height, int depth, FixedArray<T> data)
+        : m_data(move(data))
+        , m_depth(depth)
+        , m_height(height)
+        , m_width(width)
+    {
+    }
+
+    FixedArray<T> m_data;
+    int m_depth;
+    int m_height;
+    int m_width;
+};
+
+}