Texture-based thick lines: Improvements to code for drawing anti-aliased lines using textures

Moved line width into a constant
Removed test code (now in imgui-tests)
Improved matching between geometry and texture rendering at non-integer sizes

imgui.h

@@ -2323,7 +2323,6 @@ struct ImFontAtlas
 
     // [Internal] Packing data
     int                         PackIdMouseCursors; // Custom texture rectangle ID for white pixel and mouse cursors
-    int                         AALineMaxWidth;     // Maximum line width to build anti-aliased textures for
     ImVector<int>               AALineRectIds;      // Custom texture rectangle IDs for anti-aliased lines
     ImVector<ImVec4>            TexUvAALines;       // UVs for anti-aliased line textures
 

imgui_demo.cpp

@@ -297,62 +297,6 @@ void ImGui::ShowDemoWindow(bool* p_open)
     ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiCond_FirstUseEver);
     ImGui::SetNextWindowSize(ImVec2(550, 680), ImGuiCond_FirstUseEver);
 
-    // Test lines
-
-    if (ImGui::Begin("Lines"))
-    {
-        ImDrawList* draw_list = ImGui::GetWindowDrawList();
-
-        const int num_cols = 16;
-        const int num_rows = 3;
-        const float line_len = 64.0f;
-        const float line_spacing = 128.0f;
-
-        static float base_rot = 0.0f;
-        ImGui::SliderFloat("Base rotation", &base_rot, 0.0f, 360.0f);
-        static float line_width = 1.0f;
-        ImGui::SliderFloat("Line width", &line_width, 1.0f, 10.0f);
-
-        ImVec2 window_pos = ImGui::GetWindowPos();
-        ImVec2 cursor_pos = ImGui::GetCursorPos();
-        ImVec2 base_pos(window_pos.x + cursor_pos.x + (line_spacing * 0.5f), window_pos.y + cursor_pos.y);
-
-        for (int i = 0; i < num_rows; i++)
-        {
-            const char* name = "";
-            switch (i)
-            {
-            case 0: name = "No AA";  draw_list->Flags &= ~ImDrawListFlags_AntiAliasedLines; break;
-            case 1: name = "AA no texturing"; draw_list->Flags |= ImDrawListFlags_AntiAliasedLines; draw_list->Flags &= ~ImDrawListFlags_TexturedAALines; break;
-            case 2: name = "AA with texturing"; draw_list->Flags |= ImDrawListFlags_AntiAliasedLines; draw_list->Flags |= ImDrawListFlags_TexturedAALines; break;
-            }
-
-            int initial_vtx_count = draw_list->VtxBuffer.Size;
-            int initial_idx_count = draw_list->IdxBuffer.Size;
-
-            for (int j = 0; j < num_cols; j++)
-            {
-                const float pi = 3.14159265359f;
-                float r = (base_rot * pi / 180.0f) + ((j * pi * 0.5f) / (num_cols - 1));
-
-                ImVec2 center = ImVec2(base_pos.x + (line_spacing * (j * 0.5f)), base_pos.y + (line_spacing * (i + 0.5f)));
-                ImVec2 start = ImVec2(center.x + (sinf(r) * line_len * 0.5f), center.y + (cosf(r) * line_len * 0.5f));
-                ImVec2 end = ImVec2(center.x - (sinf(r) * line_len * 0.5f), center.y - (cosf(r) * line_len * 0.5f));
-
-                draw_list->AddLine(start, end, IM_COL32(255, 255, 255, 255), line_width);
-            }
-
-            ImGui::SetCursorPosY(cursor_pos.y + (i * line_spacing));
-            ImGui::Text("%s - %d vertices, %d indices", name, draw_list->VtxBuffer.Size - initial_vtx_count, draw_list->IdxBuffer.Size - initial_idx_count);
-        }
-
-        ImGui::SetCursorPosY(cursor_pos.y + (num_rows * line_spacing));
-
-        //ImGui::Spacing(); ImGui::Spacing(); ImGui::Spacing();
-        //ImGui::Image(ImGui::GetFont()->ContainerAtlas->TexID, ImVec2((float)ImGui::GetFont()->ContainerAtlas->TexWidth, (float)ImGui::GetFont()->ContainerAtlas->TexHeight));
-    }
-    ImGui::End();
-
     // Main body of the Demo window starts here.
     if (!ImGui::Begin("Dear ImGui Demo", p_open, window_flags))
     {

imgui_draw.cpp

@@ -676,13 +676,11 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         const float AA_SIZE = 1.0f;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
 
-        const int integer_thickness = (int)thickness;
+        // The -0.5f here is to better match the geometry-based code, and also shift the transition point from one width texture to another off the integer values (where it will be less noticeable)
+        const int integer_thickness = ImMax((int)(thickness - 0.5f), 1);
 
         // Do we want to draw this line using a texture?
-        bool use_textures = (Flags & ImDrawListFlags_TexturedAALines) &&
-            (integer_thickness >= 1) &&
-            (integer_thickness <= _Data->Font->ContainerAtlas->AALineMaxWidth) &&
-            ImGui::GetIO().KeyShift; // FIXME-AALINES: Remove this debug code
+        bool use_textures = (Flags & ImDrawListFlags_TexturedAALines) && (integer_thickness <= IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX);
 
         // We should never hit this, because NewFrame() doesn't set ImDrawListFlags_TexturedAALines unless ImFontAtlasFlags_NoAALines is off
         IM_ASSERT_PARANOID((!use_textures) || (!(_Data->Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoAALines)));
@@ -1707,8 +1705,6 @@ ImFontAtlas::ImFontAtlas()
     TexUvScale = ImVec2(0.0f, 0.0f);
     TexUvWhitePixel = ImVec2(0.0f, 0.0f);
     PackIdMouseCursors = -1;
-
-    AALineMaxWidth = 8;
 }
 
 ImFontAtlas::~ImFontAtlas()
@@ -2401,7 +2397,7 @@ void ImFontAtlasBuildRegisterAALineCustomRects(ImFontAtlas* atlas)
     if ((atlas->Flags & ImFontAtlasFlags_NoAALines))
         return;
 
-    const int max = atlas->AALineMaxWidth;
+    const int max = IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX;
 
     for (int n = 0; n < max; n++)
     {
@@ -2420,7 +2416,7 @@ void ImFontAtlasBuildAALinesTexData(ImFontAtlas* atlas)
         return;
 
     const int w = atlas->TexWidth;
-    const unsigned int max = atlas->AALineMaxWidth;
+    const unsigned int max = IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX;
 
     for (unsigned int n = 0; n < max; n++)
     {

imgui_internal.h

@@ -529,6 +529,9 @@ struct IMGUI_API ImChunkStream
 #define IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER             1
 #endif
 
+// The maximum line width to build anti-aliased textures for
+#define IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX                      65
+
 // 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.
 struct IMGUI_API ImDrawListSharedData