Gondwana.Rendering.Backbuffers.GpuBackbuffer Class Reference

Provides a fully GPU-rendered backbuffer implementation using SkiaSharp and OpenGL. More...

Inheritance diagram for Gondwana.Rendering.Backbuffers.GpuBackbuffer:

Public Member Functions
	GpuBackbuffer (int width, int height)
	Initializes a new instance of the GpuBackbuffer class with the specified dimensions.
void	Initialize (GRContext grContext, int width, int height)
	Creates (or recreates) the GPU render-target surface for this backbuffer.
bool	EnsureInitialized (GRContext context)
	Initializes on the owning GL thread, or applies an explicit logical resolution request. Adapter dimensions are deliberately absent: window resize never reallocates this surface. Returns true when a new surface needs its first complete frame.
void	RecordFrame ()
	Records that one frame has been rendered. Called by the platform adapter on every PaintSurface callback so the engine can compute the actual rendered FPS.
override void	Dispose ()
	Releases all resources used by this GpuBackbuffer.
Public Member Functions inherited from Gondwana.Rendering.Backbuffers.BackbufferBase
virtual byte[]	ToByteArray (SKEncodedImageFormat format=SKEncodedImageFormat.Png, int quality=100)
	Converts the current image to a byte array in the specified format and quality.

Properties
int	TargetFps [get, set]
	Gets or sets the target frame rate associated with this GPU backbuffer.
bool	VSync = true [get, set]
	Gets or sets a value indicating whether vertical synchronisation (vsync) is enabled.
int	MsaaSampleCount [get, set]
	Gets or sets the number of MSAA (multisample anti-aliasing) samples used when creating the GPU render-target surface.
int	ActualMsaaSampleCount [get]
	Gets the sample count used by the currently active GPU render-target surface.
int	MaxSupportedMsaaSampleCount [get]
	Gets the maximum MSAA sample count reported by the active GPU context for SKColorType.Rgba8888 render-target surfaces.
override bool	IsGlThreadRendered [get]
override SKCanvas	Canvas [get]
	Gets the SkiaSharp canvas for drawing operations.
Properties inherited from Gondwana.Rendering.Backbuffers.BackbufferBase
SKCanvas	Canvas [get]
	Gets the SkiaSharp canvas used for drawing operations on this backbuffer.
SKPaint	FogPaint [get, set]
	Gets or sets the paint object used to render fog effects.
SKPaint	GridLinePaint [get, set]
	Gets or sets the paint settings used to render grid lines.
SKPaint	CollisionBoxPaint [get, set]
	Gets or sets the paint settings used to render collision boxes.
int	Width [get]
	Gets the current Backbuffer width in a thread-safe manner.
int	Height [get]
	Gets the current Backbuffer height in a thread-safe manner.
SKColor	ClearColor [get, set]
	Gets or sets the color used to clear the drawing surface.
virtual bool	IsGlThreadRendered [get]
	Gets a value indicating whether this backbuffer is rendered on the GL thread rather than the engine's background render thread.

Additional Inherited Members
Protected Member Functions inherited from Gondwana.Rendering.Backbuffers.BackbufferBase
	BackbufferBase (int width, int height)
	Initializes a new instance of the BackbufferBase class with the specified dimensions.
void	UpdateSize (int width, int height)
	Updates the stored backbuffer dimensions and raises the SizeChanged event.
Protected Attributes inherited from Gondwana.Rendering.Backbuffers.BackbufferBase
readonly SKPaint	_fillPaint
	Paint used to fill cleared regions of the backbuffer with the current ClearColor.

Detailed Description

Provides a fully GPU-rendered backbuffer implementation using SkiaSharp and OpenGL.

Architecture (GL-thread rendering): All rendering operations (tile drawing, canvas operations) and presentation happen on the GL thread, driven by WinFormGpuRenderSurfaceAdapter from within SKGLControl.PaintSurface. The engine's background loop skips this surface entirely (see IsGlThreadRendered). No CPU↔GPU data transfer occurs for the backbuffer contents; tiles are rasterised directly into an off-screen GPU render target and then blitted to the window surface in a single GPU draw call.

Before the first Initialize call the backbuffer uses a temporary CPU raster surface (identical to BitmapBackbuffer) so that the host can always be in a valid state. Once a GRContext becomes available on the GL thread, Initialize replaces that with a proper GPU surface.

Thread safety: After Initialize has been called, all methods and properties that access or mutate GL state must be invoked from the GL thread (the thread on which the GRContext is current). The engine loop guarantees this by checking IsGlThreadRendered before touching the backbuffer. Configuration properties such as VSync, MsaaSampleCount, and TargetFps may be updated from other threads because they modify managed configuration state only. In particular, changing MsaaSampleCount records a new configuration revision; any required GPU surface recreation is deferred until the next owning GL-thread EnsureInitialized call.

Definition at line 39 of file GpuBackbuffer.cs.

Constructor & Destructor Documentation

GpuBackbuffer()

Gondwana.Rendering.Backbuffers.GpuBackbuffer.GpuBackbuffer	(	int	width,
		int	height )

Initializes a new instance of the GpuBackbuffer class with the specified dimensions.

Parameters

width	The initial width of the backbuffer in pixels.
height	The initial height of the backbuffer in pixels.

Definition at line 184 of file GpuBackbuffer.cs.

Member Function Documentation

Dispose()

override void Gondwana.Rendering.Backbuffers.GpuBackbuffer.Dispose ( )

virtual

Releases all resources used by this GpuBackbuffer.

Reimplemented from Gondwana.Rendering.Backbuffers.BackbufferBase.

Definition at line 420 of file GpuBackbuffer.cs.

EnsureInitialized()

bool Gondwana.Rendering.Backbuffers.GpuBackbuffer.EnsureInitialized

(

GRContext

context

)

Initializes on the owning GL thread, or applies an explicit logical resolution request. Adapter dimensions are deliberately absent: window resize never reallocates this surface. Returns true when a new surface needs its first complete frame.

Parameters

context

The context.

Returns

true if initialization succeeded; otherwise, false.

Definition at line 255 of file GpuBackbuffer.cs.

Initialize()

void Gondwana.Rendering.Backbuffers.GpuBackbuffer.Initialize	(	GRContext	grContext,
		int	width,
		int	height )

Creates (or recreates) the GPU render-target surface for this backbuffer.

Called from the owning GL thread for initial setup, an explicit logical resolution change, or an MSAA configuration change. Replaces the current surface with a hardware-accelerated off-screen render target backed by grContext .

Parameters

grContext	The active Skia GPU context. Must not be null.
width	The new surface width in pixels.
height	The new surface height in pixels.

Definition at line 215 of file GpuBackbuffer.cs.

RecordFrame()

void Gondwana.Rendering.Backbuffers.GpuBackbuffer.RecordFrame

(

)

Records that one frame has been rendered. Called by the platform adapter on every PaintSurface callback so the engine can compute the actual rendered FPS.

Property Documentation

ActualMsaaSampleCount

int Gondwana.Rendering.Backbuffers.GpuBackbuffer.ActualMsaaSampleCount

get

Gets the sample count used by the currently active GPU render-target surface.

Before the first GPU initialization this reports 1 for the temporary CPU surface. If the requested MsaaSampleCount is unsupported and surface creation falls back to non-MSAA rendering, this property reports 1 while MsaaSampleCount continues to report the requested value.

Definition at line 160 of file GpuBackbuffer.cs.

Canvas

override SKCanvas Gondwana.Rendering.Backbuffers.GpuBackbuffer.Canvas

get

Gets the SkiaSharp canvas for drawing operations.

Definition at line 277 of file GpuBackbuffer.cs.

IsGlThreadRendered

override bool Gondwana.Rendering.Backbuffers.GpuBackbuffer.IsGlThreadRendered

get

Always returns true. The engine loop will skip this surface; the platform adapter drives rendering from SKGLControl.PaintSurface.

Definition at line 202 of file GpuBackbuffer.cs.

MaxSupportedMsaaSampleCount

int Gondwana.Rendering.Backbuffers.GpuBackbuffer.MaxSupportedMsaaSampleCount

get

Gets the maximum MSAA sample count reported by the active GPU context for SKColorType.Rgba8888 render-target surfaces.

Before the first GPU initialization this reports 1. A value of 1 means the active context reports no multisample support for Gondwana's GPU render-target color type.

Definition at line 170 of file GpuBackbuffer.cs.

MsaaSampleCount

int Gondwana.Rendering.Backbuffers.GpuBackbuffer.MsaaSampleCount

getset

Gets or sets the number of MSAA (multisample anti-aliasing) samples used when creating the GPU render-target surface.

This property only applies to GpuBackbuffer; other backbuffer types ignore it.

This value is kept in sync with Gondwana.Configuration.EngineConfiguration.MsaaSampleCount (which propagates its value to all registered GPU backbuffers). A value of 1 disables MSAA. Common values are 2, 4, or 8, subject to hardware support.

Changing this property on an already-initialized backbuffer schedules the GPU render-target surface for recreation. The new sample count is applied by the next owning GL-thread EnsureInitialized call; callers do not need to resize the backbuffer.

If the requested sample count is not supported by the hardware or driver, Initialize will automatically fall back to a sample count of 1 (no MSAA) so the surface is always valid.

The MSAA sample count. Values less than 1 are clamped to 1. The default is 1.

Definition at line 129 of file GpuBackbuffer.cs.

TargetFps

int Gondwana.Rendering.Backbuffers.GpuBackbuffer.TargetFps

getset

Gets or sets the target frame rate associated with this GPU backbuffer.

This value is kept in sync with Gondwana.Configuration.EngineConfiguration.TargetFPS (which propagates its value to all registered GPU backbuffers). The engine's own foreground cycle — not the backbuffer — is responsible for throttling the frame rate; see Gondwana.Configuration.EngineConfiguration.TargetFPS for details.

The desired frames per second. Negative values are clamped to zero. The default is 60.

Definition at line 73 of file GpuBackbuffer.cs.

VSync

bool Gondwana.Rendering.Backbuffers.GpuBackbuffer.VSync = true

getset

Gets or sets a value indicating whether vertical synchronisation (vsync) is enabled.

This property only applies to GpuBackbuffer; other backbuffer types ignore it.

This value is kept in sync with Gondwana.Configuration.EngineConfiguration.VSync (which propagates its value to all registered GPU backbuffers). The value is read by the platform adapter (e.g. WinFormGpuRenderSurfaceAdapter) at the start of each PaintSurface call and applied to the underlying GLControl.VSync property when it changes. Enabling vsync prevents screen tearing but caps the frame rate to the monitor refresh rate. Disabling vsync allows higher frame rates at the cost of potential tearing.

true to synchronise presentation with the monitor refresh; otherwise false. The default is true.

Definition at line 99 of file GpuBackbuffer.cs.