From e45847d99af3bc153ac95c181fa82b294c1b427a Mon Sep 17 00:00:00 2001 From: thedmd Date: Sat, 13 Feb 2021 19:42:23 +0100 Subject: [PATCH] Add version of PathArcTo() and PathArcToFast() with adaptive rendering quality. (#3491) --- docs/CHANGELOG.txt | 6 +- imgui.h | 4 +- imgui_draw.cpp | 144 ++++++++++++++++++++++++++++++++++++++++----- imgui_internal.h | 14 +++-- 4 files changed, 148 insertions(+), 20 deletions(-) diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt index 9cbe13d8e091..69d2706af58e 100644 --- a/docs/CHANGELOG.txt +++ b/docs/CHANGELOG.txt @@ -75,9 +75,13 @@ Other Changes: This can currently only ever be set by the Freetype renderer. - imgui_freetype: Added ImGuiFreeTypeBuilderFlags_Bitmap flag to request Freetype loading bitmap data. This may have an effect on size and must be called with correct size values. (#3879) [@metarutaiga] +- ImDrawList: PathArcTo() now supports "int num_segments = 0" (new default) and adaptively tesselate. + The adapative tesselation uses look up tables, tends to be faster than old PathArcTo() while maintaining + quality for large arcs (tesselation quality derived from "style.CircleTessellationMaxError") (#3491) [@thedmd] +- ImDrawList: PathArcToFast() also adaptively tesselate efficiently. This means that large rounded corners + in e.g. hi-dpi settings will generally look better. (#3491) [@thedmd] - ImDrawList: AddCircle, AddCircleFilled(): Tweaked default segment count calculation to honor MaxError with more accuracy. Made default segment count always even for better looking result. (#3808) [@thedmd] -- ImDrawList: AddCircle, AddCircleFilled(): New default for style. - Backends: Android: Added native Android backend. (#3446) [@duddel] - Backends: Win32: Added ImGui_ImplWin32_EnableAlphaCompositing() to facilitate experimenting with alpha compositing and transparent windows. (#2766, #3447 etc.). diff --git a/imgui.h b/imgui.h index 6379975c0e58..21f479f3e079 100644 --- a/imgui.h +++ b/imgui.h @@ -2436,7 +2436,7 @@ struct ImDrawList inline void PathLineToMergeDuplicate(const ImVec2& pos) { if (_Path.Size == 0 || memcmp(&_Path.Data[_Path.Size - 1], &pos, 8) != 0) _Path.push_back(pos); } 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, ImDrawFlags flags = 0, float thickness = 1.0f) { AddPolyline(_Path.Data, _Path.Size, col, flags, 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 PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, 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 PathBezierCubicCurveTo(const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments = 0); // Cubic Bezier (4 control points) IMGUI_API void PathBezierQuadraticCurveTo(const ImVec2& p2, const ImVec2& p3, int num_segments = 0); // Quadratic Bezier (3 control points) @@ -2482,6 +2482,8 @@ struct ImDrawList IMGUI_API void _OnChangedTextureID(); IMGUI_API void _OnChangedVtxOffset(); IMGUI_API int _CalcCircleAutoSegmentCount(float radius) const; + IMGUI_API void _PathArcToFastEx(const ImVec2& center, float radius, int a_min_sample, int a_max_sample, int a_step); + IMGUI_API void _PathArcToN(const ImVec2& center, float radius, float a_min, float a_max, int num_segments); }; // All draw data to render a Dear ImGui frame diff --git a/imgui_draw.cpp b/imgui_draw.cpp index 9a03b56c923c..b08f3fd4aa62 100644 --- a/imgui_draw.cpp +++ b/imgui_draw.cpp @@ -374,18 +374,22 @@ ImDrawListSharedData::ImDrawListSharedData() const float a = ((float)i * 2 * IM_PI) / (float)IM_ARRAYSIZE(ArcFastVtx); ArcFastVtx[i] = ImVec2(ImCos(a), ImSin(a)); } + ArcFastRadiusCutoff = IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC_R(IM_DRAWLIST_ARCFAST_SAMPLE_MAX, CircleSegmentMaxError); } void ImDrawListSharedData::SetCircleTessellationMaxError(float max_error) { if (CircleSegmentMaxError == max_error) return; + + IM_ASSERT(max_error > 0.0f); CircleSegmentMaxError = max_error; for (int i = 0; i < IM_ARRAYSIZE(CircleSegmentCounts); i++) { const float radius = (float)i; CircleSegmentCounts[i] = (ImU8)((i > 0) ? IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC(radius, CircleSegmentMaxError) : 0); } + ArcFastRadiusCutoff = IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC_R(IM_DRAWLIST_ARCFAST_SAMPLE_MAX, CircleSegmentMaxError); } // Initialize before use in a new frame. We always have a command ready in the buffer. @@ -1026,32 +1030,86 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun } } -// 0: East, 3: South, 6: West, 9: North, 12: East -void ImDrawList::PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12) +void ImDrawList::_PathArcToFastEx(const ImVec2& center, float radius, int a_min_sample, int a_max_sample, int a_step) { if (radius <= 0.0f) { _Path.push_back(center); return; } - IM_ASSERT(a_min_of_12 <= a_max_of_12); + IM_ASSERT(a_min_sample <= a_max_sample); - // For legacy reason the PathArcToFast() always takes angles where 2*PI is represented by 12, - // but it is possible to set IM_DRAWLIST_ARCFAST_TESSELATION_MULTIPLIER to a higher value. This should compile to a no-op otherwise. -#if IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER != 1 - a_min_of_12 *= IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER; - a_max_of_12 *= IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER; -#endif + // Calculate arc auto segment step size + if (a_step <= 0) + a_step = IM_DRAWLIST_ARCFAST_SAMPLE_MAX / _CalcCircleAutoSegmentCount(radius); + + // Make sure we never do steps larger than one quarter of the circle + a_step = ImClamp(a_step, 1, IM_DRAWLIST_ARCFAST_TABLE_SIZE / 4); + + // Normalize a_min_sample to always start lie in [0..IM_DRAWLIST_ARCFAST_SAMPLE_MAX] range. + if (a_min_sample < 0) + { + int normalized_sample = a_min_sample % IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + if (normalized_sample < 0) + normalized_sample += IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + a_max_sample += (normalized_sample - a_min_sample); + a_min_sample = normalized_sample; + } + + const int sample_range = a_max_sample - a_min_sample; + const int a_next_step = a_step; + + int samples = sample_range + 1; + bool extra_max_sample = false; + if (a_step > 1) + { + samples = sample_range / a_step + 1; + const int overstep = sample_range % a_step; + + if (overstep > 0) + { + extra_max_sample = true; + samples++; - _Path.reserve(_Path.Size + (a_max_of_12 - a_min_of_12 + 1)); - for (int a = a_min_of_12; a <= a_max_of_12; a++) + // When we have overstep to avoid awkwardly looking one long line and one tiny one at the end, + // distribute first step range evenly between them by reducing first step size. + if (sample_range > 0) + a_step -= (a_step - overstep) / 2; + } + } + + _Path.resize(_Path.Size + samples); + ImVec2* out_ptr = _Path.Data + (_Path.Size - samples); + + int sample_index = a_min_sample; + for (int a = a_min_sample; a <= a_max_sample; a += a_step, sample_index += a_step, a_step = a_next_step) + { + // a_step is clamped to IM_DRAWLIST_ARCFAST_SAMPLE_MAX, so we have guaranteed that it will not wrap over range twice or more + if (sample_index >= IM_DRAWLIST_ARCFAST_SAMPLE_MAX) + sample_index -= IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + + const ImVec2 s = _Data->ArcFastVtx[sample_index]; + out_ptr->x = center.x + s.x * radius; + out_ptr->y = center.y + s.y * radius; + out_ptr++; + } + + if (extra_max_sample) { - const ImVec2& c = _Data->ArcFastVtx[a % IM_ARRAYSIZE(_Data->ArcFastVtx)]; - _Path.push_back(ImVec2(center.x + c.x * radius, center.y + c.y * radius)); + int normalized_max_sample = a_max_sample % IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + if (normalized_max_sample < 0) + normalized_max_sample += IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + + const ImVec2 s = _Data->ArcFastVtx[normalized_max_sample]; + out_ptr->x = center.x + s.x * radius; + out_ptr->y = center.y + s.y * radius; + out_ptr++; } + + IM_ASSERT_PARANOID(_Path.Data + _Path.Size == out_ptr); } -void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments) +void ImDrawList::_PathArcToN(const ImVec2& center, float radius, float a_min, float a_max, int num_segments) { if (radius <= 0.0f) { @@ -1070,6 +1128,64 @@ void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, floa } } +// 0: East, 3: South, 6: West, 9: North, 12: East +void ImDrawList::PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12) +{ + if (radius <= 0.0f) + { + _Path.push_back(center); + return; + } + IM_ASSERT(a_min_of_12 <= a_max_of_12); + _PathArcToFastEx(center, radius, a_min_of_12 * IM_DRAWLIST_ARCFAST_SAMPLE_MAX / 12, a_max_of_12 * IM_DRAWLIST_ARCFAST_SAMPLE_MAX / 12, 0); +} + +void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments) +{ + if (radius <= 0.0f) + { + _Path.push_back(center); + return; + } + IM_ASSERT(a_min <= a_max); + + if (num_segments > 0) + { + _PathArcToN(center, radius, a_min, a_max, num_segments); + return; + } + + // Automatic segment count + if (radius <= _Data->ArcFastRadiusCutoff) + { + // We are going to use precomputed values for mid samples. + // Determine first and last sample in lookup table that belong to the arc. + const int a_min_sample = (int)ImCeil(IM_DRAWLIST_ARCFAST_SAMPLE_MAX * a_min / (IM_PI * 2.0f)); + const int a_max_sample = (int)( IM_DRAWLIST_ARCFAST_SAMPLE_MAX * a_max / (IM_PI * 2.0f)); + const int a_mid_samples = ImMax(a_max_sample - a_min_sample, 0); + + const float a_min_segment_angle = a_min_sample * IM_PI * 2.0f / IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + const float a_max_segment_angle = a_max_sample * IM_PI * 2.0f / IM_DRAWLIST_ARCFAST_SAMPLE_MAX; + const bool a_emit_start = (a_min_segment_angle - a_min) > 0.0f; + const bool a_emit_end = (a_max - a_max_segment_angle) > 0.0f; + + _Path.reserve(_Path.Size + (a_mid_samples + 1 + (a_emit_start ? 1 : 0) + (a_emit_end ? 1 : 0))); + if (a_emit_start) + _Path.push_back(ImVec2(center.x + ImCos(a_min) * radius, center.y + ImSin(a_min) * radius)); + if (a_max_sample >= a_min_sample) + _PathArcToFastEx(center, radius, a_min_sample, a_max_sample, 0); + if (a_emit_end) + _Path.push_back(ImVec2(center.x + ImCos(a_max) * radius, center.y + ImSin(a_max) * radius)); + } + else + { + const float arc_length = a_max - a_min; + const int circle_segment_count = _CalcCircleAutoSegmentCount(radius); + const int arc_segment_count = ImMax((int)ImCeil(circle_segment_count * arc_length / (IM_PI * 2.0f)), (int)(2.0f * IM_PI / arc_length)); + _PathArcToN(center, radius, a_min, a_max, arc_segment_count); + } +} + ImVec2 ImBezierCubicCalc(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, float t) { float u = 1.0f - t; diff --git a/imgui_internal.h b/imgui_internal.h index 15d37e4ef5f6..b03030150150 100644 --- a/imgui_internal.h +++ b/imgui_internal.h @@ -636,10 +636,15 @@ struct IMGUI_API ImChunkStream #define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_MAX 512 #define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC(_RAD,_MAXERROR) ImClamp(IM_ROUNDUP_TO_EVEN((int)ImCeil(IM_PI / ImAcos(1 - ImMin((_MAXERROR), (_RAD)) / (_RAD)))), IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_MIN, IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_MAX) -// ImDrawList: You may set this to higher values (e.g. 2 or 3) to increase tessellation of fast rounded corners path. -#ifndef IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER -#define IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER 1 +// Raw equation from IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC rewritten for 'r' and 'error'. +#define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC_R(_N,_MAXERROR) ((_MAXERROR) / (1 - ImCos(IM_PI / ImMax((float)(_N), IM_PI)))) +#define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC_ERROR(_N,_RAD) ((1 - ImCos(IM_PI / ImMax((float)(_N), IM_PI))) / (_RAD)) + +// ImDrawList: Lookup table size for adaptive arc drawing, cover full circle. +#ifndef IM_DRAWLIST_ARCFAST_TABLE_SIZE +#define IM_DRAWLIST_ARCFAST_TABLE_SIZE 48 // Number of samples in lookup table. #endif +#define IM_DRAWLIST_ARCFAST_SAMPLE_MAX IM_DRAWLIST_ARCFAST_TABLE_SIZE // Sample index _PathArcToFastEx() for 360 angle. // Data shared between all ImDrawList instances // You may want to create your own instance of this if you want to use ImDrawList completely without ImGui. In that case, watch out for future changes to this structure. @@ -654,7 +659,8 @@ struct IMGUI_API ImDrawListSharedData ImDrawListFlags InitialFlags; // Initial flags at the beginning of the frame (it is possible to alter flags on a per-drawlist basis afterwards) // [Internal] Lookup tables - ImVec2 ArcFastVtx[12 * IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER]; // FIXME: Bake rounded corners fill/borders in atlas + ImVec2 ArcFastVtx[IM_DRAWLIST_ARCFAST_TABLE_SIZE]; // Sample points on the quarter of the circle. + float ArcFastRadiusCutoff; // Cutoff radius after which arc drawing will fallback to slower PathArcTo() ImU8 CircleSegmentCounts[64]; // Precomputed segment count for given radius before we calculate it dynamically (to avoid calculation overhead) const ImVec4* TexUvLines; // UV of anti-aliased lines in the atlas