Add ImDrawList::AddQuadBezierCurve(), ImDrawList::PathQuadBezierCurveTo() (#3127, #3664, #3665)

imgui.h

@@ -2357,8 +2357,9 @@ struct ImDrawList
     IMGUI_API void  AddText(const ImFont* font, float font_size, const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL, float wrap_width = 0.0f, const ImVec4* cpu_fine_clip_rect = NULL);
     IMGUI_API void  AddPolyline(const ImVec2* points, int num_points, ImU32 col, bool closed, float thickness);
     IMGUI_API void  AddConvexPolyFilled(const ImVec2* points, int num_points, ImU32 col); // Note: Anti-aliased filling requires points to be in clockwise order.
-    IMGUI_API void  AddBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col, float thickness, int num_segments = 0);
-
+    IMGUI_API void  AddQuadBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, ImU32 col, float thickness, int num_segments = 0);                     // Quad Bezier (3 control points)
+    IMGUI_API void  AddBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col, float thickness, int num_segments = 0);       // Cubic Bezier (4 control points)
+    
     // Image primitives
     // - Read FAQ to understand what ImTextureID is.
     // - "p_min" and "p_max" represent the upper-left and lower-right corners of the rectangle.
@@ -2374,8 +2375,9 @@ struct ImDrawList
     inline    void  PathFillConvex(ImU32 col)                                   { AddConvexPolyFilled(_Path.Data, _Path.Size, col); _Path.Size = 0; }  // Note: Anti-aliased filling requires points to be in clockwise order.
     inline    void  PathStroke(ImU32 col, bool closed, float thickness = 1.0f)  { AddPolyline(_Path.Data, _Path.Size, col, closed, thickness); _Path.Size = 0; }
     IMGUI_API void  PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments = 10);
-    IMGUI_API void  PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12);                                            // Use precomputed angles for a 12 steps circle
-    IMGUI_API void  PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments = 0);
+    IMGUI_API void  PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12);                        // Use precomputed angles for a 12 steps circle
+    IMGUI_API void  PathQuadBezierCurveTo(const ImVec2& p2, const ImVec2& p3, int num_segments = 0);                            // Quad Bezier (3 control points)
+    IMGUI_API void  PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments = 0);              // Cubic Bezier (4 control points)
     IMGUI_API void  PathRect(const ImVec2& rect_min, const ImVec2& rect_max, float rounding = 0.0f, ImDrawCornerFlags rounding_corners = ImDrawCornerFlags_All);
 
     // Advanced

imgui_demo.cpp

@@ -6917,11 +6917,13 @@ static void ShowExampleAppCustomRendering(bool* p_open)
 
             // Draw a bunch of primitives
             ImGui::Text("All primitives");
-            static float sz = 36.0f;
+            static float sz = 33.0f;
             static float thickness = 3.0f;
             static int ngon_sides = 6;
             static bool circle_segments_override = false;
             static int circle_segments_override_v = 12;
+            static bool curve_segments_override = false;
+            static int curve_segments_override_v = 8;
             static ImVec4 colf = ImVec4(1.0f, 1.0f, 0.4f, 1.0f);
             ImGui::DragFloat("Size", &sz, 0.2f, 2.0f, 72.0f, "%.0f");
             ImGui::DragFloat("Thickness", &thickness, 0.05f, 1.0f, 8.0f, "%.02f");
@@ -6930,6 +6932,10 @@ static void ShowExampleAppCustomRendering(bool* p_open)
             ImGui::SameLine(0.0f, ImGui::GetStyle().ItemInnerSpacing.x);
             if (ImGui::SliderInt("Circle segments", &circle_segments_override_v, 3, 40))
                 circle_segments_override = true;
+            ImGui::Checkbox("##curvessegmentoverride", &curve_segments_override);
+            ImGui::SameLine(0.0f, ImGui::GetStyle().ItemInnerSpacing.x);
+            if (ImGui::SliderInt("Curves segments", &curve_segments_override_v, 3, 40))
+                curve_segments_override = true;
             ImGui::ColorEdit4("Color", &colf.x);
 
             const ImVec2 p = ImGui::GetCursorScreenPos();
@@ -6939,6 +6945,7 @@ static void ShowExampleAppCustomRendering(bool* p_open)
             const ImDrawCornerFlags corners_all = ImDrawCornerFlags_All;
             const ImDrawCornerFlags corners_tl_br = ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_BotRight;
             const int circle_segments = circle_segments_override ? circle_segments_override_v : 0;
+            const int curve_segments = curve_segments_override ? curve_segments_override_v : 0;
             float x = p.x + 4.0f;
             float y = p.y + 4.0f;
             for (int n = 0; n < 2; n++)
@@ -6955,7 +6962,8 @@ static void ShowExampleAppCustomRendering(bool* p_open)
                 draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y), col, th);                                       x += sz + spacing;  // Horizontal line (note: drawing a filled rectangle will be faster!)
                 draw_list->AddLine(ImVec2(x, y), ImVec2(x, y + sz), col, th);                                       x += spacing;       // Vertical line (note: drawing a filled rectangle will be faster!)
                 draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y + sz), col, th);                                  x += sz + spacing;  // Diagonal line
-                draw_list->AddBezierCurve(ImVec2(x, y), ImVec2(x + sz*1.3f, y + sz*0.3f), ImVec2(x + sz - sz*1.3f, y + sz - sz*0.3f), ImVec2(x + sz, y + sz), col, th);
+                draw_list->AddQuadBezierCurve(ImVec2(x, y + sz * 0.6), ImVec2(x + sz * 0.5, y - sz * 0.4), ImVec2(x + sz, y + sz), col, th, curve_segments); x += sz + spacing;  // Quad Bezier (3 control points)                   
+                draw_list->AddBezierCurve(ImVec2(x, y), ImVec2(x + sz * 1.3f, y + sz * 0.3f), ImVec2(x + sz - sz * 1.3f, y + sz - sz * 0.3f), ImVec2(x + sz, y + sz), col, th, curve_segments);
                 x = p.x + 4;
                 y += sz + spacing;
             }

imgui_draw.cpp

@@ -1050,6 +1050,7 @@ void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, floa
     }
 }
 
+// Cubic bezier
 ImVec2 ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t)
 {
     float u = 1.0f - t;
@@ -1060,13 +1061,14 @@ ImVec2 ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const
     return ImVec2(w1*p1.x + w2*p2.x + w3*p3.x + w4*p4.x, w1*p1.y + w2*p2.y + w3*p3.y + w4*p4.y);
 }
 
+// Cubic bezier
 // Closely mimics BezierClosestPointCasteljauStep() in imgui.cpp
 static void PathBezierToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4, float tess_tol, int level)
 {
     float dx = x4 - x1;
     float dy = y4 - y1;
-    float d2 = ((x2 - x4) * dy - (y2 - y4) * dx);
-    float d3 = ((x3 - x4) * dy - (y3 - y4) * dx);
+    float d2 = (x2 - x4) * dy - (y2 - y4) * dx;
+    float d3 = (x3 - x4) * dy - (y3 - y4) * dx;
     d2 = (d2 >= 0) ? d2 : -d2;
     d3 = (d3 >= 0) ? d3 : -d3;
     if ((d2 + d3) * (d2 + d3) < tess_tol * (dx * dx + dy * dy))
@@ -1075,17 +1077,18 @@ static void PathBezierToCasteljau(ImVector<ImVec2>* path, float x1, float y1, fl
     }
     else if (level < 10)
     {
-        float x12 = (x1 + x2)*0.5f,       y12 = (y1 + y2)*0.5f;
-        float x23 = (x2 + x3)*0.5f,       y23 = (y2 + y3)*0.5f;
-        float x34 = (x3 + x4)*0.5f,       y34 = (y3 + y4)*0.5f;
-        float x123 = (x12 + x23)*0.5f,    y123 = (y12 + y23)*0.5f;
-        float x234 = (x23 + x34)*0.5f,    y234 = (y23 + y34)*0.5f;
-        float x1234 = (x123 + x234)*0.5f, y1234 = (y123 + y234)*0.5f;
-        PathBezierToCasteljau(path, x1, y1,        x12, y12,    x123, y123,  x1234, y1234, tess_tol, level + 1);
-        PathBezierToCasteljau(path, x1234, y1234,  x234, y234,  x34, y34,    x4, y4,       tess_tol, level + 1);
+        float x12 = (x1 + x2) * 0.5f, y12 = (y1 + y2) * 0.5f;
+        float x23 = (x2 + x3) * 0.5f, y23 = (y2 + y3) * 0.5f;
+        float x34 = (x3 + x4) * 0.5f, y34 = (y3 + y4) * 0.5f;
+        float x123 = (x12 + x23) * 0.5f, y123 = (y12 + y23) * 0.5f;
+        float x234 = (x23 + x34) * 0.5f, y234 = (y23 + y34) * 0.5f;
+        float x1234 = (x123 + x234) * 0.5f, y1234 = (y123 + y234) * 0.5f;
+        PathBezierToCasteljau(path, x1, y1, x12, y12, x123, y123, x1234, y1234, tess_tol, level + 1);
+        PathBezierToCasteljau(path, x1234, y1234, x234, y234, x34, y34, x4, y4, tess_tol, level + 1);
     }
 }
 
+// Cubic bezier
 void ImDrawList::PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments)
 {
     ImVec2 p1 = _Path.back();
@@ -1101,6 +1104,51 @@ void ImDrawList::PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImV
     }
 }
 
+// Quadratic bezier
+ImVec2 ImQuadBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, float t)
+{
+    float u = 1.0f - t;
+    float w1 = u * u;
+    float w2 = 2 * u * t;
+    float w3 = t * t;
+    return ImVec2(w1 * p1.x + w2 * p2.x + w3 * p3.x, w1 * p1.y + w2 * p2.y + w3 * p3.y);
+}
+
+// Quadratic bezier
+static void PathQuadBezierToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float tess_tol, int level)
+{
+    float dx = x3 - x1, dy = y3 - y1;
+    float det = (x2 - x3) * dy - (y2 - y3) * dx;
+    if (det * det * 4.0f < tess_tol * (dx * dx + dy * dy))
+    {
+        path->push_back(ImVec2(x3, y3));
+    }
+    else if (level < 10)
+    {
+        float x12 = (x1 + x2) * 0.5f, y12 = (y1 + y2) * 0.5f;
+        float x23 = (x2 + x3) * 0.5f, y23 = (y2 + y3) * 0.5f;
+        float x123 = (x12 + x23) * 0.5f, y123 = (y12 + y23) * 0.5f;
+        PathQuadBezierToCasteljau(path, x1, y1, x12, y12, x123, y123, tess_tol, level + 1);
+        PathQuadBezierToCasteljau(path, x123, y123, x23, y23, x3, y3, tess_tol, level + 1);
+    }
+}
+
+// Quadratic bezier
+void ImDrawList::PathQuadBezierCurveTo(const ImVec2& p2, const ImVec2& p3, int num_segments)
+{
+    ImVec2 p1 = _Path.back();
+    if (num_segments == 0)
+    {
+        PathQuadBezierToCasteljau(&_Path, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, _Data->CurveTessellationTol, 0); // Auto-tessellated
+    }
+    else
+    {
+        float t_step = 1.0f / (float)num_segments;
+        for (int i_step = 1; i_step <= num_segments; i_step++)
+            _Path.push_back(ImQuadBezierCalc(p1, p2, p3, t_step * i_step));
+    }
+}
+
 void ImDrawList::PathRect(const ImVec2& a, const ImVec2& b, float rounding, ImDrawCornerFlags rounding_corners)
 {
     rounding = ImMin(rounding, ImFabs(b.x - a.x) * ( ((rounding_corners & ImDrawCornerFlags_Top)  == ImDrawCornerFlags_Top)  || ((rounding_corners & ImDrawCornerFlags_Bot)   == ImDrawCornerFlags_Bot)   ? 0.5f : 1.0f ) - 1.0f);
@@ -1310,6 +1358,17 @@ void ImDrawList::AddNgonFilled(const ImVec2& center, float radius, ImU32 col, in
     PathFillConvex(col);
 }
 
+// Quad Bezier takes 3 controls points
+void ImDrawList::AddQuadBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, ImU32 col, float thickness, int num_segments)
+{
+    if ((col & IM_COL32_A_MASK) == 0)
+        return;
+
+    PathLineTo(p1);
+    PathQuadBezierCurveTo(p2, p3, num_segments);
+    PathStroke(col, false, thickness);
+}
+
 // Cubic Bezier takes 4 controls points
 void ImDrawList::AddBezierCurve(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col, float thickness, int num_segments)
 {