[GPU/D3D12] Letterboxing cropping to action-safe area

src/xenia/gpu/d3d12/d3d12_graphics_system.cc

@@ -10,7 +10,9 @@
 #include "xenia/gpu/d3d12/d3d12_graphics_system.h"
 
 #include "xenia/base/logging.h"
+#include "xenia/base/math.h"
 #include "xenia/gpu/d3d12/d3d12_command_processor.h"
+#include "xenia/gpu/draw_util.h"
 #include "xenia/ui/d3d12/d3d12_util.h"
 #include "xenia/xbox.h"
 
@@ -265,22 +267,39 @@ void D3D12GraphicsSystem::Swap(xe::ui::UIEvent* e) {
     return;
   }
 
+  uint32_t window_width, window_height;
+  display_context_->GetSwapChainSize(window_width, window_height);
+
+  int32_t target_x, target_y;
+  uint32_t target_width, target_height;
+  draw_util::GetPresentArea(swap_state.width, swap_state.height, window_width,
+                            window_height, target_x, target_y, target_width,
+                            target_height);
+  // For safety.
+  target_x = clamp(target_x, int32_t(D3D12_VIEWPORT_BOUNDS_MIN),
+                   int32_t(D3D12_VIEWPORT_BOUNDS_MAX));
+  target_y = clamp(target_y, int32_t(D3D12_VIEWPORT_BOUNDS_MIN),
+                   int32_t(D3D12_VIEWPORT_BOUNDS_MAX));
+  target_width = std::min(
+      target_width, uint32_t(int32_t(D3D12_VIEWPORT_BOUNDS_MAX) - target_x));
+  target_height = std::min(
+      target_height, uint32_t(int32_t(D3D12_VIEWPORT_BOUNDS_MAX) - target_y));
+
   auto command_list = display_context_->GetSwapCommandList();
-  uint32_t swap_width, swap_height;
-  display_context_->GetSwapChainSize(swap_width, swap_height);
+  // Assuming the window has already been cleared to the needed letterbox color.
   D3D12_VIEWPORT viewport;
-  viewport.TopLeftX = 0.0f;
-  viewport.TopLeftY = 0.0f;
-  viewport.Width = float(swap_width);
-  viewport.Height = float(swap_height);
+  viewport.TopLeftX = float(target_x);
+  viewport.TopLeftY = float(target_y);
+  viewport.Width = float(target_width);
+  viewport.Height = float(target_height);
   viewport.MinDepth = 0.0f;
   viewport.MaxDepth = 0.0f;
   command_list->RSSetViewports(1, &viewport);
   D3D12_RECT scissor;
   scissor.left = 0;
   scissor.top = 0;
-  scissor.right = swap_width;
-  scissor.bottom = swap_height;
+  scissor.right = window_width;
+  scissor.bottom = window_height;
   command_list->RSSetScissorRects(1, &scissor);
   command_list->SetDescriptorHeaps(1, &swap_srv_heap);
   StretchTextureToFrontBuffer(

src/xenia/gpu/draw_util.cc

@@ -9,6 +9,7 @@
 
 #include "xenia/gpu/draw_util.h"
 
+#include <algorithm>
 #include <cmath>
 #include <cstring>
 
@@ -31,6 +32,36 @@ DEFINE_bool(
     "for certain games like GTA IV to work).",
     "GPU");
 
+DEFINE_bool(
+    present_stretch, true,
+    "Whether to rescale the image, instead of maintaining the original pixel "
+    "size, when presenting to the window. When this is disabled, other "
+    "positioning options are ignored.",
+    "GPU");
+DEFINE_bool(
+    present_letterbox, true,
+    "Maintain aspect ratio when stretching by displaying bars around the image "
+    "when there's no more overscan area to crop out.",
+    "GPU");
+// https://github.com/MonoGame/MonoGame/issues/4697#issuecomment-217779403
+// Using the value from DirectXTK (5% cropped out from each side, thus 90%),
+// which is not exactly the Xbox One title-safe area, but close, and within the
+// action-safe area:
+// https://github.com/microsoft/DirectXTK/blob/1e80a465c6960b457ef9ab6716672c1443a45024/Src/SimpleMath.cpp#L144
+// XNA TitleSafeArea is 80%, but it's very conservative, designed for CRT, and
+// is the title-safe area rather than the action-safe area.
+// 90% is also exactly the fraction of 16:9 height in 16:10.
+DEFINE_int32(
+    present_safe_area_x, 90,
+    "Percentage of the image width that can be kept when presenting to "
+    "maintain aspect ratio without letterboxing or stretching.",
+    "GPU");
+DEFINE_int32(
+    present_safe_area_y, 90,
+    "Percentage of the image height that can be kept when presenting to "
+    "maintain aspect ratio without letterboxing or stretching.",
+    "GPU");
+
 namespace xe {
 namespace gpu {
 namespace draw_util {
@@ -589,6 +620,87 @@ ResolveCopyShaderIndex ResolveInfo::GetCopyShader(
   return shader;
 }
 
+void GetPresentArea(uint32_t source_width, uint32_t source_height,
+                    uint32_t window_width, uint32_t window_height,
+                    int32_t& target_x_out, int32_t& target_y_out,
+                    uint32_t& target_width_out, uint32_t& target_height_out) {
+  if (!cvars::present_stretch) {
+    target_x_out = (int32_t(window_width) - int32_t(source_width)) / 2;
+    target_y_out = (int32_t(window_height) - int32_t(source_height)) / 2;
+    target_width_out = source_width;
+    target_height_out = source_height;
+    return;
+  }
+  // Prevent division by zero.
+  if (!source_width || !source_height) {
+    target_x_out = 0;
+    target_y_out = 0;
+    target_width_out = 0;
+    target_height_out = 0;
+    return;
+  }
+  if (uint64_t(window_width) * source_height >
+      uint64_t(source_width) * window_height) {
+    // The window is wider that the source - crop along Y, then letterbox or
+    // stretch along X.
+    uint32_t present_safe_area;
+    if (cvars::present_safe_area_y > 0 && cvars::present_safe_area_y < 100) {
+      present_safe_area = uint32_t(cvars::present_safe_area_y);
+    } else {
+      present_safe_area = 100;
+    }
+    uint32_t target_height =
+        uint32_t(uint64_t(window_width) * source_height / source_width);
+    bool letterbox = false;
+    if (target_height * present_safe_area > window_height * 100) {
+      // Don't crop out more than the safe area margin - letterbox or stretch.
+      target_height = window_height * 100 / present_safe_area;
+      letterbox = true;
+    }
+    if (letterbox && cvars::present_letterbox) {
+      uint32_t target_width =
+          uint32_t(uint64_t(source_width) * window_height * 100 /
+                   (source_height * present_safe_area));
+      target_x_out = (int32_t(window_width) - int32_t(target_width)) / 2;
+      target_width_out = target_width;
+    } else {
+      target_x_out = 0;
+      target_width_out = window_width;
+    }
+    target_y_out = (int32_t(window_height) - int32_t(target_height)) / 2;
+    target_height_out = target_height;
+  } else {
+    // The window is taller than the source - crop along X, then letterbox or
+    // stretch along Y.
+    uint32_t present_safe_area;
+    if (cvars::present_safe_area_x > 0 && cvars::present_safe_area_x < 100) {
+      present_safe_area = uint32_t(cvars::present_safe_area_x);
+    } else {
+      present_safe_area = 100;
+    }
+    uint32_t target_width =
+        uint32_t(uint64_t(window_height) * source_width / source_height);
+    bool letterbox = false;
+    if (target_width * present_safe_area > window_width * 100) {
+      // Don't crop out more than the safe area margin - letterbox or stretch.
+      target_width = window_width * 100 / present_safe_area;
+      letterbox = true;
+    }
+    if (letterbox && cvars::present_letterbox) {
+      uint32_t target_height =
+          uint32_t(uint64_t(source_height) * window_width * 100 /
+                   (source_width * present_safe_area));
+      target_y_out = (int32_t(window_height) - int32_t(target_height)) / 2;
+      target_height_out = target_height;
+    } else {
+      target_y_out = 0;
+      target_height_out = window_height;
+    }
+    target_x_out = (int32_t(window_width) - int32_t(target_width)) / 2;
+    target_width_out = target_width;
+  }
+}
+
 }  // namespace draw_util
 }  // namespace gpu
 }  // namespace xe

src/xenia/gpu/draw_util.h

@@ -272,6 +272,14 @@ bool GetResolveInfo(const RegisterFile& regs, const Memory& memory,
                     TraceWriter& trace_writer, uint32_t resolution_scale,
                     bool edram_16_as_minus_1_to_1, ResolveInfo& info_out);
 
+// Taking user configuration - stretching or letterboxing, overscan region to
+// crop to fill while maintaining the aspect ratio - into account, returns the
+// area where the frame should be presented in the host window.
+void GetPresentArea(uint32_t source_width, uint32_t source_height,
+                    uint32_t window_width, uint32_t window_height,
+                    int32_t& target_x_out, int32_t& target_y_out,
+                    uint32_t& target_width_out, uint32_t& target_height_out);
+
 }  // namespace draw_util
 }  // namespace gpu
 }  // namespace xe