/// <summary>
/// Updates the front face based on the current front face and the origin.
/// </summary>
/// <param name="yControl">Y control register value, where the origin is located</param>
/// <param name="frontFace">Front face</param>
private void UpdateFrontFace(YControl yControl, FrontFace frontFace)
{
bool isUpperLeftOrigin = !yControl.HasFlag(YControl.TriangleRastFlip);
if (isUpperLeftOrigin)
{
frontFace = frontFace == FrontFace.CounterClockwise ? FrontFace.Clockwise : FrontFace.CounterClockwise;
}
_context.Renderer.Pipeline.SetFrontFace(frontFace);
}
/// <summary>
/// Updates host viewport transform and clipping state based on current GPU state.
/// </summary>
/// <param name="state">Current GPU state</param>
private void UpdateViewportTransform(GpuState state)
{
DepthMode depthMode = state.Get <DepthMode>(MethodOffset.DepthMode);
_context.Renderer.Pipeline.SetDepthMode(depthMode);
YControl yControl = state.Get <YControl>(MethodOffset.YControl);
bool flipY = yControl.HasFlag(YControl.NegateY);
Origin origin = yControl.HasFlag(YControl.TriangleRastFlip) ? Origin.LowerLeft : Origin.UpperLeft;
_context.Renderer.Pipeline.SetOrigin(origin);
// The triangle rast flip flag only affects rasterization, the viewport is not flipped.
// Setting the origin mode to upper left on the host, however, not only affects rasterization,
// but also flips the viewport.
// We negate the effects of flipping the viewport by flipping it again using the viewport swizzle.
if (origin == Origin.UpperLeft)
{
flipY = !flipY;
}
Span <Viewport> viewports = stackalloc Viewport[Constants.TotalViewports];
for (int index = 0; index < Constants.TotalViewports; index++)
{
var transform = state.Get <ViewportTransform>(MethodOffset.ViewportTransform, index);
var extents = state.Get <ViewportExtents> (MethodOffset.ViewportExtents, index);
float x = transform.TranslateX - MathF.Abs(transform.ScaleX);
float y = transform.TranslateY - MathF.Abs(transform.ScaleY);
float width = MathF.Abs(transform.ScaleX) * 2;
float height = MathF.Abs(transform.ScaleY) * 2;
float scale = TextureManager.RenderTargetScale;
if (scale != 1f)
{
x *= scale;
y *= scale;
width *= scale;
height *= scale;
}
RectangleF region = new RectangleF(x, y, width, height);
ViewportSwizzle swizzleX = transform.UnpackSwizzleX();
ViewportSwizzle swizzleY = transform.UnpackSwizzleY();
ViewportSwizzle swizzleZ = transform.UnpackSwizzleZ();
ViewportSwizzle swizzleW = transform.UnpackSwizzleW();
if (transform.ScaleX < 0)
{
swizzleX ^= ViewportSwizzle.NegativeFlag;
}
if (flipY)
{
swizzleY ^= ViewportSwizzle.NegativeFlag;
}
if (transform.ScaleY < 0)
{
swizzleY ^= ViewportSwizzle.NegativeFlag;
}
if (transform.ScaleZ < 0)
{
swizzleZ ^= ViewportSwizzle.NegativeFlag;
}
viewports[index] = new Viewport(
region,
swizzleX,
swizzleY,
swizzleZ,
swizzleW,
extents.DepthNear,
extents.DepthFar);
}
_context.Renderer.Pipeline.SetViewports(0, viewports);
}
