Internals: Added ImTriangleBarycentricCoords() helper. Renamed ImIsPointInTriangle() to ImTriangleContainsPoint(), with different arg order.

imgui.cpp

@@ -900,7 +900,7 @@ void ImGuiIO::AddInputCharactersUTF8(const char* utf8_chars)
 #define IM_NEWLINE "\n"
 #endif
 
-bool ImIsPointInTriangle(const ImVec2& p, const ImVec2& a, const ImVec2& b, const ImVec2& c)
+bool ImTriangleContainsPoint(ImVec2 a, ImVec2 b, ImVec2 c, ImVec2 p)
 {
     bool b1 = ((p.x - b.x) * (a.y - b.y) - (p.y - b.y) * (a.x - b.x)) < 0.0f;
     bool b2 = ((p.x - c.x) * (b.y - c.y) - (p.y - c.y) * (b.x - c.x)) < 0.0f;
@@ -908,6 +908,17 @@ bool ImIsPointInTriangle(const ImVec2& p, const ImVec2& a, const ImVec2& b, cons
     return ((b1 == b2) && (b2 == b3));
 }
 
+void ImTriangleBarycentricCoords(ImVec2 a, ImVec2 b, ImVec2 c, ImVec2 p, float& out_u, float& out_v, float& out_w)
+{
+    ImVec2 v0 = b - a;
+    ImVec2 v1 = c - a;
+    ImVec2 v2 = p - a;
+    const float denom = v0.x * v1.y - v1.x * v0.y;
+    out_v = (v2.x * v1.y - v1.x * v2.y) / denom;
+    out_w = (v0.x * v2.y - v2.x * v0.y) / denom;
+    out_u = 1.0f - out_v - out_w;
+}
+
 int ImStricmp(const char* str1, const char* str2)
 {
     int d;
@@ -8954,7 +8965,7 @@ bool ImGui::BeginMenu(const char* label, bool enabled)
                 ta.x += (window->Pos.x < next_window->Pos.x) ? -0.5f : +0.5f;   // to avoid numerical issues
                 tb.y = ta.y + ImMax((tb.y - extra) - ta.y, -100.0f);            // triangle is maximum 200 high to limit the slope and the bias toward large sub-menus // FIXME: Multiply by fb_scale?
                 tc.y = ta.y + ImMin((tc.y + extra) - ta.y, +100.0f);
-                moving_within_opened_triangle = ImIsPointInTriangle(g.IO.MousePos, ta, tb, tc);
+                moving_within_opened_triangle = ImTriangleContainsPoint(ta, tb, tc, g.IO.MousePos);
                 //window->DrawList->PushClipRectFullScreen(); window->DrawList->AddTriangleFilled(ta, tb, tc, moving_within_opened_triangle ? IM_COL32(0,128,0,128) : IM_COL32(128,0,0,128)); window->DrawList->PopClipRect(); // Debug
             }
         }

imgui_internal.h

@@ -90,7 +90,8 @@ IMGUI_API int           ImTextCountUtf8BytesFromStr(const ImWchar* in_text, cons
 IMGUI_API ImU32         ImHash(const void* data, int data_size, ImU32 seed = 0);    // Pass data_size==0 for zero-terminated strings
 IMGUI_API void*         ImFileLoadToMemory(const char* filename, const char* file_open_mode, int* out_file_size = NULL, int padding_bytes = 0);
 IMGUI_API FILE*         ImFileOpen(const char* filename, const char* file_open_mode);         
-IMGUI_API bool          ImIsPointInTriangle(const ImVec2& p, const ImVec2& a, const ImVec2& b, const ImVec2& c);
+IMGUI_API bool          ImTriangleContainsPoint(ImVec2 a, ImVec2 b, ImVec2 c, ImVec2 p);
+IMGUI_API void          ImTriangleBarycentricCoords(ImVec2 a, ImVec2 b, ImVec2 c, ImVec2 p, float& out_u, float& out_v, float& out_w);
 static inline bool      ImCharIsSpace(int c)            { return c == ' ' || c == '\t' || c == 0x3000; }
 static inline bool      ImIsPowerOfTwo(int v)           { return v != 0 && (v & (v - 1)) == 0; }
 static inline int       ImUpperPowerOfTwo(int v)        { v--; v |= v >> 1; v |= v >> 2; v |= v >> 4; v |= v >> 8; v |= v >> 16; v++; return v; }