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AddCircle, AddCircleFilled: Add auto-calculation of circle segment counts

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This commit is contained in:
Ben Carter
2019-12-09 15:57:24 +09:00
committed by omar
parent 2eda3585e7
commit 051ce0765e
5 changed files with 62 additions and 8 deletions
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7
imgui.cpp
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@@ -988,6 +988,7 @@ ImGuiStyle::ImGuiStyle()
AntiAliasedLines = true; // Enable anti-aliasing on lines/borders. Disable if you are really short on CPU/GPU.
AntiAliasedFill = true; // Enable anti-aliasing on filled shapes (rounded rectangles, circles, etc.)
CurveTessellationTol = 1.25f; // Tessellation tolerance when using PathBezierCurveTo() without a specific number of segments. Decrease for highly tessellated curves (higher quality, more polygons), increase to reduce quality.
CircleSegmentMaxError = 0.75f; // Maximum error (in pixels) allowed when using AddCircle()/AddCircleFilled() or drawing rounded corner rectangles with no explicit segment count specified. Decrease for higher quality but more geometry.
// Default theme
ImGui::StyleColorsDark(this);
@@ -3560,6 +3561,7 @@ static void NewFrameSanityChecks()
IM_ASSERT(g.IO.Fonts->Fonts.Size > 0 && "Font Atlas not built. Did you call io.Fonts->GetTexDataAsRGBA32() / GetTexDataAsAlpha8() ?");
IM_ASSERT(g.IO.Fonts->Fonts[0]->IsLoaded() && "Font Atlas not built. Did you call io.Fonts->GetTexDataAsRGBA32() / GetTexDataAsAlpha8() ?");
IM_ASSERT(g.Style.CurveTessellationTol > 0.0f && "Invalid style setting!");
IM_ASSERT(g.Style.CircleSegmentMaxError > 0.0f && "Invalid style setting!");
IM_ASSERT(g.Style.Alpha >= 0.0f && g.Style.Alpha <= 1.0f && "Invalid style setting. Alpha cannot be negative (allows us to avoid a few clamps in color computations)!");
IM_ASSERT(g.Style.WindowMinSize.x >= 1.0f && g.Style.WindowMinSize.y >= 1.0f && "Invalid style setting.");
IM_ASSERT(g.Style.WindowMenuButtonPosition == ImGuiDir_None || g.Style.WindowMenuButtonPosition == ImGuiDir_Left || g.Style.WindowMenuButtonPosition == ImGuiDir_Right);
@@ -3622,6 +3624,7 @@ void ImGui::NewFrame()
IM_ASSERT(g.Font->IsLoaded());
g.DrawListSharedData.ClipRectFullscreen = ImVec4(0.0f, 0.0f, g.IO.DisplaySize.x, g.IO.DisplaySize.y);
g.DrawListSharedData.CurveTessellationTol = g.Style.CurveTessellationTol;
g.DrawListSharedData.CircleSegmentMaxError = g.Style.CircleSegmentMaxError;
g.DrawListSharedData.InitialFlags = ImDrawListFlags_None;
if (g.Style.AntiAliasedLines)
g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLines;
@@ -3630,6 +3633,10 @@ void ImGui::NewFrame()
if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)
g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AllowVtxOffset;
// Recalculate circle segment counts if the segment error has changed
if (g.DrawListSharedData.CircleSegmentMaxError != g.DrawListSharedData.CircleSegmentCountsMaxCircleSegmentError)
g.DrawListSharedData.RecalculateCircleSegmentCounts();
g.BackgroundDrawList.Clear();
g.BackgroundDrawList.PushTextureID(g.IO.Fonts->TexID);
g.BackgroundDrawList.PushClipRectFullScreen();

9
imgui.h
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@@ -1359,6 +1359,7 @@ struct ImGuiStyle
bool AntiAliasedLines; // Enable anti-aliasing on lines/borders. Disable if you are really tight on CPU/GPU.
bool AntiAliasedFill; // Enable anti-aliasing on filled shapes (rounded rectangles, circles, etc.)
float CurveTessellationTol; // Tessellation tolerance when using PathBezierCurveTo() without a specific number of segments. Decrease for highly tessellated curves (higher quality, more polygons), increase to reduce quality.
float CircleSegmentMaxError; // Maximum error (in pixels) allowed when using AddCircle()/AddCircleFilled() or drawing rounded corner rectangles with no explicit segment count specified. Decrease for higher quality but more geometry.
ImVec4 Colors[ImGuiCol_COUNT];
IMGUI_API ImGuiStyle();
@@ -1948,10 +1949,10 @@ struct ImDrawList
IMGUI_API void AddQuadFilled(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, ImU32 col);
IMGUI_API void AddTriangle(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, ImU32 col, float thickness = 1.0f);
IMGUI_API void AddTriangleFilled(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, ImU32 col);
IMGUI_API void AddCircle(const ImVec2& center, float radius, ImU32 col, int num_segments = 12, float thickness = 1.0f);
IMGUI_API void AddCircleFilled(const ImVec2& center, float radius, ImU32 col, int num_segments = 12);
IMGUI_API void AddNgon(const ImVec2& center, float radius, ImU32 col, int num_segments, float thickness = 1.0f);
IMGUI_API void AddNgonFilled(const ImVec2& center, float radius, ImU32 col, int num_segments);
IMGUI_API void AddCircle(const ImVec2& center, float radius, ImU32 col, int num_segments = 12, float thickness = 1.0f); // Draw a circle - use num_segments <= 0 to automatically calculate tessellation (preferred). Use AddNgon() instead if you need a specific segment count.
IMGUI_API void AddCircleFilled(const ImVec2& center, float radius, ImU32 col, int num_segments = 12); // Draw a filled circle - use num_segments <= 0 to automatically calculate tessellation (preferred). Use AddNgonFilled() instead if you need a specific segment count.
IMGUI_API void AddNgon(const ImVec2& center, float radius, ImU32 col, int num_segments, float thickness = 1.0f); // Draw an n-gon with a specific number of sides. Use AddCircle() instead if you want an actual circle and don't care about the exact side count.
IMGUI_API void AddNgonFilled(const ImVec2& center, float radius, ImU32 col, int num_segments); // Draw a filled n-gon with a specific number of sides. Use AddCircleFilled() instead if you want an actual circle and don't care about the exact side count.
IMGUI_API void AddText(const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL);
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);

5
imgui_demo.cpp
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@@ -3502,6 +3502,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
ImGui::PushItemWidth(100);
ImGui::DragFloat("Curve Tessellation Tolerance", &style.CurveTessellationTol, 0.02f, 0.10f, FLT_MAX, "%.2f", 2.0f);
if (style.CurveTessellationTol < 0.10f) style.CurveTessellationTol = 0.10f;
ImGui::DragFloat("Max circle segment error", &style.CircleSegmentMaxError, 0.01f, 0.1f, 10.0f, "%.2f", 1.0f);
ImGui::DragFloat("Global Alpha", &style.Alpha, 0.005f, 0.20f, 1.0f, "%.2f"); // Not exposing zero here so user doesn't "lose" the UI (zero alpha clips all widgets). But application code could have a toggle to switch between zero and non-zero.
ImGui::PopItemWidth();
@@ -4471,7 +4472,7 @@ static void ShowExampleAppCustomRendering(bool* p_open)
// First line uses a thickness of 1.0f, second line uses the configurable thickness
float th = (n == 0) ? 1.0f : thickness;
draw_list->AddNgon(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, ngon_sides, th); x += sz + spacing; // n-gon
draw_list->AddCircle(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, 20, th); x += sz + spacing; // Circle
draw_list->AddCircle(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, 0, th); x += sz + spacing; // Circle
draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 0.0f, corners_none, th); x += sz + spacing; // Square
draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f, corners_all, th); x += sz + spacing; // Square with all rounded corners
draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f, corners_tl_br, th); x += sz + spacing; // Square with two rounded corners
@@ -4485,7 +4486,7 @@ static void ShowExampleAppCustomRendering(bool* p_open)
y += sz + spacing;
}
draw_list->AddNgonFilled(ImVec2(x + sz * 0.5f, y + sz * 0.5f), sz*0.5f, col, ngon_sides); x += sz + spacing; // n-gon
draw_list->AddCircleFilled(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, 32); x += sz + spacing; // Circle
draw_list->AddCircleFilled(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, 0); x += sz + spacing; // Circle
draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col); x += sz + spacing; // Square
draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f); x += sz + spacing; // Square with all rounded corners
draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f, corners_tl_br); x += sz + spacing; // Square with two rounded corners

41
imgui_draw.cpp
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@@ -348,6 +348,8 @@ ImDrawListSharedData::ImDrawListSharedData()
Font = NULL;
FontSize = 0.0f;
CurveTessellationTol = 0.0f;
CircleSegmentMaxError = 0.0f;
CircleSegmentCountsMaxCircleSegmentError = -FLT_MIN; // Impossible value to force recalculation
ClipRectFullscreen = ImVec4(-8192.0f, -8192.0f, +8192.0f, +8192.0f);
InitialFlags = ImDrawListFlags_None;
@@ -1083,11 +1085,34 @@ void ImDrawList::AddTriangleFilled(const ImVec2& p1, const ImVec2& p2, const ImV
PathFillConvex(col);
}
void ImDrawListSharedData::RecalculateCircleSegmentCounts()
{
for (int i = 0; i < NumCircleSegmentCounts; i++)
{
const float radius = i + 1.0f;
CircleSegmentCounts[i] = ImClamp((int)((IM_PI * 2.0f) / ImAcos((radius - CircleSegmentMaxError) / radius)), 3, 10000);
}
CircleSegmentCountsMaxCircleSegmentError = CircleSegmentMaxError;
}
void ImDrawList::AddCircle(const ImVec2& center, float radius, ImU32 col, int num_segments, float thickness)
{
if ((col & IM_COL32_A_MASK) == 0 || num_segments <= 2)
if ((col & IM_COL32_A_MASK) == 0 || (radius <= 0.0f))
return;
// Calculate number of segments if required
if (num_segments <= 0)
{
int radius_int = (int)radius;
if (radius_int <= ImDrawListSharedData::NumCircleSegmentCounts)
num_segments = _Data->CircleSegmentCounts[radius_int - 1]; // Use cached value
else
num_segments = ImClamp((int)((IM_PI * 2.0f) / ImAcos((radius - _Data->CircleSegmentMaxError) / radius)), 3, 10000);
}
else
num_segments = ImClamp(num_segments, 3, 10000); // Clamp to avoid drawing insanely tessellated shapes
// Because we are filling a closed shape we remove 1 from the count of segments/points
const float a_max = (IM_PI * 2.0f) * ((float)num_segments - 1.0f) / (float)num_segments;
PathArcTo(center, radius - 0.5f, 0.0f, a_max, num_segments - 1);
@@ -1096,9 +1121,21 @@ void ImDrawList::AddCircle(const ImVec2& center, float radius, ImU32 col, int nu
void ImDrawList::AddCircleFilled(const ImVec2& center, float radius, ImU32 col, int num_segments)
{
if ((col & IM_COL32_A_MASK) == 0 || num_segments <= 2)
if ((col & IM_COL32_A_MASK) == 0 || (radius <= 0.0f))
return;
// Calculate number of segments if required
if (num_segments <= 0)
{
int radius_int = (int)radius;
if (radius_int <= ImDrawListSharedData::NumCircleSegmentCounts)
num_segments = _Data->CircleSegmentCounts[radius_int - 1]; // Use cached value
else
num_segments = ImClamp((int)((IM_PI * 2.0f) / ImAcos((radius - _Data->CircleSegmentMaxError) / radius)), 3, 10000);
}
else
num_segments = ImClamp(num_segments, 3, 10000); // Clamp to avoid drawing insanely tessellated shapes
// Because we are filling a closed shape we remove 1 from the count of segments/points
const float a_max = (IM_PI * 2.0f) * ((float)num_segments - 1.0f) / (float)num_segments;
PathArcTo(center, radius, 0.0f, a_max, num_segments - 1);

8
imgui_internal.h
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@@ -855,6 +855,7 @@ struct IMGUI_API ImDrawListSharedData
ImFont* Font; // Current/default font (optional, for simplified AddText overload)
float FontSize; // Current/default font size (optional, for simplified AddText overload)
float CurveTessellationTol; // Tessellation tolerance when using PathBezierCurveTo()
float CircleSegmentMaxError; // Number of circle segments to use per pixel of radius for AddCircle() etc
ImVec4 ClipRectFullscreen; // Value for PushClipRectFullscreen()
ImDrawListFlags InitialFlags; // Initial flags at the beginning of the frame (it is possible to alter flags on a per-drawlist basis afterwards)
@@ -862,6 +863,13 @@ struct IMGUI_API ImDrawListSharedData
// FIXME: Bake rounded corners fill/borders in atlas
ImVec2 CircleVtx12[12];
// Cached circle segment counts for the first <n> radii (to avoid calculation overhead)
static const int NumCircleSegmentCounts = 64;// Number of circle segment counts to cache (i.e. the maximum radius before we calculate dynamically)
int CircleSegmentCounts[NumCircleSegmentCounts]; // The segment count for radius (array index + 1)
float CircleSegmentCountsMaxCircleSegmentError; // The MaxCircleSegmentError used to calculate these counts
void RecalculateCircleSegmentCounts(); // Recalculate circle segment counts based on the current MaxCircleSegmentError
ImDrawListSharedData();
};