Gui: add helpers for rotation

touhouworldcup · Jul 4, 2023 · 1846352 · 1846352
1 parent 759610e
commit 1846352
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Showing 2 changed files with 33 additions and 0 deletions.
diff --git a/thprac/src/thprac/thprac_gui_components.cpp b/thprac/src/thprac/thprac_gui_components.cpp
@@ -1,8 +1,38 @@
 #include "thprac_gui_components.h"
+#include "imgui_internal.h"
 #include <Shlwapi.h>
 
 namespace THPrac
 {
+    int rotation_start_index;
+    void ImRotateStart()
+    {
+        rotation_start_index = ImGui::GetWindowDrawList()->VtxBuffer.Size;
+    }
+
+    ImVec2 ImRotationCenter()
+    {
+        ImVec2 l(FLT_MAX, FLT_MAX), u(-FLT_MAX, -FLT_MAX); // bounds
+
+        const auto& buf = ImGui::GetWindowDrawList()->VtxBuffer;
+        for (int i = rotation_start_index; i < buf.Size; i++)
+            l = ImMin(l, buf[i].pos), u = ImMax(u, buf[i].pos);
+
+        return ImVec2((l.x + u.x) / 2, (l.y + u.y) / 2); // or use _ClipRectStack?
+    }
+
+    ImVec2 operator-(const ImVec2& l, const ImVec2& r) { return { l.x - r.x, l.y - r.y }; }
+
+    void ImRotateEnd(float rad, ImVec2 center)
+    {
+        float s = sin(rad), c = cos(rad);
+        center = ImRotate(center, s, c) - center;
+
+        auto& buf = ImGui::GetWindowDrawList()->VtxBuffer;
+        for (int i = rotation_start_index; i < buf.Size; i++)
+            buf[i].pos = ImRotate(buf[i].pos, s, c) - center;
+    }
+
 	namespace Gui
 	{
 		bool GuiNavFocus::mGlobalDisable = false;

diff --git a/thprac/src/thprac/thprac_gui_components.h b/thprac/src/thprac/thprac_gui_components.h
@@ -14,6 +14,9 @@
 #include "utils/utils.h"
 
 namespace THPrac {
+void ImRotateStart();
+ImVec2 ImRotationCenter();
+void ImRotateEnd(float rad, ImVec2 center = ImRotationCenter());
 namespace Gui {
     class GameGuiWnd {
     public: