From 3831d50ab96c33d24cec3e048d9c7839d2d64074 Mon Sep 17 00:00:00 2001 From: Rokas Kupstys Date: Tue, 17 Dec 2019 16:29:12 +0200 Subject: [PATCH] Add ImBezierClosestPoint() function which returns a point on bezier curve which is closed to a specified point. --- imgui.cpp | 66 ++++++++++++++++++++++++++++++++++++++++++++++++ imgui_draw.cpp | 21 ++++++++------- imgui_internal.h | 3 +++ 3 files changed, 81 insertions(+), 9 deletions(-) diff --git a/imgui.cpp b/imgui.cpp index dff12b624..d114f9ef8 100644 --- a/imgui.cpp +++ b/imgui.cpp @@ -1109,6 +1109,72 @@ void ImGuiIO::ClearInputCharacters() // [SECTION] MISC HELPERS/UTILITIES (Geometry, String, Format, Hash, File functions) //----------------------------------------------------------------------------- +ImVec2 ImBezierClosestPoint(const ImVec2& p, const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments) +{ + IM_ASSERT(num_segments > 0); + ImVec2 p_last = p1; + ImVec2 p_closest; + float p_closest_dist2 = FLT_MAX; + float t_step = 1.0f / (float)num_segments; + for (int i_step = 1; i_step <= num_segments; i_step++) + { + ImVec2 p_current = ImBezierCalc(p1, p2, p3, p4, t_step * i_step); + ImVec2 p_line = ImLineClosestPoint(p_last, p_current, p); + float dist2 = ImLengthSqr(p - p_line); + if (dist2 < p_closest_dist2) + { + p_closest = p_line; + p_closest_dist2 = dist2; + } + p_last = p_current; + } + return p_closest; +} + +// Closely mimics PathBezierToCasteljau() in imgui_draw.cpp +static void ClosestPointBezierCasteljau(const ImVec2& p, ImVec2& p_closest, ImVec2& p_last, float& p_closest_dist2, 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); + d2 = (d2 >= 0) ? d2 : -d2; + d3 = (d3 >= 0) ? d3 : -d3; + if ((d2+d3) * (d2+d3) < tess_tol * (dx*dx + dy*dy)) + { + ImVec2 p_current(x4, y4); + ImVec2 p_line = ImLineClosestPoint(p_last, p_current, p); + float dist2 = ImLengthSqr(p - p_line); + if (dist2 < p_closest_dist2) + { + p_closest = p_line; + p_closest_dist2 = dist2; + } + p_last = p_current; + } + 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; + ClosestPointBezierCasteljau(p, p_closest, p_last, p_closest_dist2, x1, y1, x12, y12, x123, y123, x1234, y1234, tess_tol, level + 1); + ClosestPointBezierCasteljau(p, p_closest, p_last, p_closest_dist2, x1234, y1234, x234, y234, x34, y34, x4, y4, tess_tol, level + 1); + } +} + +ImVec2 ImBezierClosestPointCasteljau(const ImVec2& p, const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float tess_tol) +{ + IM_ASSERT(tess_tol > 0.0f); + ImVec2 p_last = p1; + ImVec2 p_closest; + float p_closest_dist2 = FLT_MAX; + ClosestPointBezierCasteljau(p, p_closest, p_last, p_closest_dist2, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y, tess_tol, 0); + return p_closest; +} + ImVec2 ImLineClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& p) { ImVec2 ap = p - a; diff --git a/imgui_draw.cpp b/imgui_draw.cpp index 9efb47311..8f913dc00 100644 --- a/imgui_draw.cpp +++ b/imgui_draw.cpp @@ -907,6 +907,17 @@ void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, floa } } +ImVec2 ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t) +{ + float u = 1.0f - t; + float w1 = u*u*u; + float w2 = 3*u*u*t; + float w3 = 3*u*t*t; + float w4 = t*t*t; + 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); +} + +// Closely mimicked by ClosestPointBezierCasteljau() in imgui.cpp static void PathBezierToCasteljau(ImVector* 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; @@ -945,15 +956,7 @@ void ImDrawList::PathBezierCurveTo(const ImVec2& p2, const ImVec2& p3, const ImV { float t_step = 1.0f / (float)num_segments; for (int i_step = 1; i_step <= num_segments; i_step++) - { - float t = t_step * i_step; - float u = 1.0f - t; - float w1 = u*u*u; - float w2 = 3*u*u*t; - float w3 = 3*u*t*t; - float w4 = t*t*t; - _Path.push_back(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)); - } + _Path.push_back(ImBezierCalc(p1, p2, p3, p4, t_step * i_step)); } } diff --git a/imgui_internal.h b/imgui_internal.h index 07fb28823..bf594bc53 100644 --- a/imgui_internal.h +++ b/imgui_internal.h @@ -340,6 +340,9 @@ static inline float ImLinearSweep(float current, float target, float speed) static inline ImVec2 ImMul(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x * rhs.x, lhs.y * rhs.y); } // Helpers: Geometry +IMGUI_API ImVec2 ImBezierCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t); +IMGUI_API ImVec2 ImBezierClosestPoint(const ImVec2& p, const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments); // For curves with explicit number of segments +IMGUI_API ImVec2 ImBezierClosestPointCasteljau(const ImVec2& p, const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float tess_tol); // For auto-tesselated curves, tess_tol = style.CurveTessellationTol IMGUI_API ImVec2 ImLineClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& p); IMGUI_API bool ImTriangleContainsPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p); IMGUI_API ImVec2 ImTriangleClosestPoint(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& p);