Fixes to allow clean 1-pixel thick lines in more use cases. PixelCenterOffset not the same as previously!

examples/directx9_example/main.cpp

@@ -22,8 +22,8 @@ struct CUSTOMVERTEX
 
 // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
 // If text or lines are blurry when integrating ImGui in your engine:
-// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.0f or 0.5f
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
+// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.5f or 0.375f
 static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
 {
     size_t total_vtx_count = 0;
@@ -82,7 +82,7 @@ static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_c
     D3DXMatrixIdentity(&mat);
     g_pd3dDevice->SetTransform(D3DTS_WORLD, &mat);
     g_pd3dDevice->SetTransform(D3DTS_VIEW, &mat);
-    D3DXMatrixOrthoOffCenterLH(&mat, 0.0f, ImGui::GetIO().DisplaySize.x, ImGui::GetIO().DisplaySize.y, 0.0f, -1.0f, +1.0f);
+    D3DXMatrixOrthoOffCenterLH(&mat, 0.5f, ImGui::GetIO().DisplaySize.x+0.5f, ImGui::GetIO().DisplaySize.y+0.5f, 0.5f, -1.0f, +1.0f);
     g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &mat);
 
     // Render command lists

examples/opengl_example/main.cpp

@@ -13,8 +13,8 @@ static GLuint fontTex;
 
 // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
 // If text or lines are blurry when integrating ImGui in your engine:
-// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.0f or 0.5f
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
+// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.5f or 0.375f
 static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
 {
     if (cmd_lists_count == 0)
@@ -151,7 +151,7 @@ void InitImGui()
     ImGuiIO& io = ImGui::GetIO();
     io.DisplaySize = ImVec2((float)w, (float)h);        // Display size, in pixels. For clamping windows positions.
     io.DeltaTime = 1.0f/60.0f;                          // Time elapsed since last frame, in seconds (in this sample app we'll override this every frame because our timestep is variable)
-    io.PixelCenterOffset = 0.5f;                        // Align OpenGL texels
+    io.PixelCenterOffset = 0.0f;                        // Align OpenGL texels
     io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;             // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
     io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
     io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;

imgui.cpp

@@ -88,8 +88,8 @@
         }
 
  - if text or lines are blurry when integrating ImGui in your engine:
-   - try adjusting ImGui::GetIO().PixelCenterOffset to 0.0f or 0.5f
    - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
+   - try adjusting ImGui::GetIO().PixelCenterOffset to 0.5f or 0.375f
 
  - some widgets carry state and requires an unique ID to do so.
    - unique ID are typically derived from a string label, an indice or a pointer.
@@ -280,7 +280,7 @@ ImGuiIO::ImGuiIO()
     LogFilename = "imgui_log.txt";
     Font = NULL;
     FontAllowScaling = false;
-    PixelCenterOffset = 0.5f;
+    PixelCenterOffset = 0.0f;
     MousePos = ImVec2(-1,-1);
     MousePosPrev = ImVec2(-1,-1);
     MouseDoubleClickTime = 0.30f;
@@ -1560,8 +1560,10 @@ static void RenderFrame(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, bool border,
     window->DrawList->AddRectFilled(p_min, p_max, fill_col, rounding);
     if (border && (window->Flags & ImGuiWindowFlags_ShowBorders))
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), window->Color(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, window->Color(ImGuiCol_Border), rounding);
+        // FIXME: I have no idea how this is working correctly but it is the best I've found that works on multiple rendering
+        const float offset = GImGui.IO.PixelCenterOffset;
+        window->DrawList->AddRect(p_min+ImVec2(1.5f-offset,1.5f-offset), p_max+ImVec2(1.0f-offset*2,1.0f-offset*2), window->Color(ImGuiCol_BorderShadow), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(0.5f-offset,0.5f-offset), p_max+ImVec2(0.0f-offset*2,0.0f-offset*2), window->Color(ImGuiCol_Border), rounding);
     }
 }
 
@@ -2768,20 +2770,21 @@ static bool CloseWindowButton(bool* open)
 
     const ImGuiID id = window->GetID("##CLOSE");
     const float size = window->TitleBarHeight() - 4.0f;
-    const ImGuiAabb bb(window->Aabb().GetTR() + ImVec2(-2.0f-size,2.0f), window->Aabb().GetTR() + ImVec2(-2.0f,2.0f+size));
+    const ImGuiAabb bb(window->Aabb().GetTR() + ImVec2(-3.0f-size,2.0f), window->Aabb().GetTR() + ImVec2(-3.0f,2.0f+size));
 
     bool hovered, held;
     bool pressed = ButtonBehaviour(bb, id, &hovered, &held, true);
 
     // Render
     const ImU32 col = window->Color((held && hovered) ? ImGuiCol_CloseButtonActive : hovered ? ImGuiCol_CloseButtonHovered : ImGuiCol_CloseButton);
-    window->DrawList->AddCircleFilled(bb.GetCenter(), ImMax(2.0f,size*0.5f-2.0f), col, 16);
+    const ImVec2 center = bb.GetCenter();
+    window->DrawList->AddCircleFilled(center, ImMax(2.0f,size*0.5f), col, 16);
 
-    const float cross_padding = 4.0f;
-    if (hovered && bb.GetWidth() >= (cross_padding+1)*2 && bb.GetHeight() >= (cross_padding+1)*2)
+    const float cross_extent = (size * 0.5f * 0.7071f) - 1.0f;
+    if (hovered)
     {
-        window->DrawList->AddLine(bb.GetTL()+ImVec2(+cross_padding,+cross_padding), bb.GetBR()+ImVec2(-cross_padding,-cross_padding), window->Color(ImGuiCol_Text));
-        window->DrawList->AddLine(bb.GetBL()+ImVec2(+cross_padding,-cross_padding), bb.GetTR()+ImVec2(-cross_padding,+cross_padding), window->Color(ImGuiCol_Text));
+        window->DrawList->AddLine(center + ImVec2(+cross_extent,+cross_extent), center + ImVec2(-cross_extent,-cross_extent), window->Color(ImGuiCol_Text));
+        window->DrawList->AddLine(center + ImVec2(+cross_extent,-cross_extent), center + ImVec2(-cross_extent,+cross_extent), window->Color(ImGuiCol_Text));
     }
 
     if (open != NULL && pressed)
@@ -4815,16 +4818,18 @@ void ImDrawList::AddVtx(const ImVec2& pos, ImU32 col)
 
 void ImDrawList::AddVtxLine(const ImVec2& a, const ImVec2& b, ImU32 col)
 {
-    const ImVec2 n = (b - a) / ImLength(b - a);
-    const ImVec2 hn = ImVec2(n.y, -n.x) * 0.5f;
-
-    AddVtx(a - hn, col);
-    AddVtx(b - hn, col);
-    AddVtx(a + hn, col);
+    const float offset = GImGui.IO.PixelCenterOffset;
+    const ImVec2 hn = (b - a) * (0.50f / ImLength(b - a));     // half normal
+    const ImVec2 hp0 = ImVec2(offset - hn.y, offset + hn.x);   // half perpendiculars + user offset
+    const ImVec2 hp1 = ImVec2(offset + hn.y, offset - hn.x);
 
-    AddVtx(b - hn, col);
-    AddVtx(b + hn, col);
-    AddVtx(a + hn, col);
+    // Two triangles makes up one line. Using triangles allows us to make draw calls.
+    AddVtx(a + hp0, col);
+    AddVtx(b + hp0, col);
+    AddVtx(a + hp1, col);
+    AddVtx(b + hp0, col);
+    AddVtx(b + hp1, col);
+    AddVtx(a + hp1, col);
 }
 
 void ImDrawList::AddLine(const ImVec2& a, const ImVec2& b, ImU32 col)
@@ -4966,10 +4971,12 @@ void ImDrawList::AddTriangleFilled(const ImVec2& a, const ImVec2& b, const ImVec
     if ((col >> 24) == 0)
         return;
 
+    const ImVec2 offset(GImGui.IO.PixelCenterOffset,GImGui.IO.PixelCenterOffset);
+
     ReserveVertices(3);
-    AddVtx(a, col);
-    AddVtx(b, col);
-    AddVtx(c, col);
+    AddVtx(a + offset, col);
+    AddVtx(b + offset, col);
+    AddVtx(c + offset, col);
 }
 
 void ImDrawList::AddCircle(const ImVec2& centre, float radius, ImU32 col, int num_segments)
@@ -4977,13 +4984,15 @@ void ImDrawList::AddCircle(const ImVec2& centre, float radius, ImU32 col, int nu
     if ((col >> 24) == 0)
         return;
 
+    const ImVec2 offset(GImGui.IO.PixelCenterOffset,GImGui.IO.PixelCenterOffset);
+
     ReserveVertices((unsigned int)num_segments*6);
     const float a_step = 2*PI/(float)num_segments;
     float a0 = 0.0f;
     for (int i = 0; i < num_segments; i++)
     {
         const float a1 = (i + 1) == num_segments ? 0.0f : a0 + a_step;
-        AddVtxLine(centre + ImVec2(cos(a0),sin(a0))*radius, centre + ImVec2(cos(a1),sin(a1))*radius, col);
+        AddVtxLine(centre + offset + ImVec2(cos(a0),sin(a0))*radius, centre + ImVec2(cos(a1),sin(a1))*radius, col);
         a0 = a1;
     }
 }
@@ -4993,15 +5002,17 @@ void ImDrawList::AddCircleFilled(const ImVec2& centre, float radius, ImU32 col,
     if ((col >> 24) == 0)
         return;
 
+    const ImVec2 offset(GImGui.IO.PixelCenterOffset,GImGui.IO.PixelCenterOffset);
+
     ReserveVertices((unsigned int)num_segments*3);
     const float a_step = 2*PI/(float)num_segments;
     float a0 = 0.0f;
     for (int i = 0; i < num_segments; i++)
     {
         const float a1 = (i + 1) == num_segments ? 0.0f : a0 + a_step;
-        AddVtx(centre + ImVec2(cos(a0),sin(a0))*radius, col);
-        AddVtx(centre + ImVec2(cos(a1),sin(a1))*radius, col);
-        AddVtx(centre, col);
+        AddVtx(centre + offset + ImVec2(cos(a0),sin(a0))*radius, col);
+        AddVtx(centre + offset + ImVec2(cos(a1),sin(a1))*radius, col);
+        AddVtx(centre + offset, col);
         a0 = a1;
     }
 }
@@ -5231,13 +5242,11 @@ void ImBitmapFont::RenderText(float size, ImVec2 pos, ImU32 col, const ImVec4& c
     const float outline = (float)Info->Outline;
 
     // Align to be pixel perfect
-    pos.x = (float)(int)pos.x + 0.5f;
-    pos.y = (float)(int)pos.y + 0.5f;
+    pos.x = (float)(int)pos.x;
+    pos.y = (float)(int)pos.y;
 
     const ImVec4 clip_rect = clip_rect_ref;
 
-    const float uv_offset = GImGui.IO.PixelCenterOffset;
-
     float x = pos.x;
     float y = pos.y;
     for (const char* s = text_begin; s < text_end; s++)
@@ -5274,10 +5283,10 @@ void ImBitmapFont::RenderText(float size, ImVec2 pos, ImU32 col, const ImVec4& c
                     continue;
                 }
 
-                const float s1 = (uv_offset + glyph->X) * tex_scale_x;
-                const float t1 = (uv_offset + glyph->Y) * tex_scale_y;
-                const float s2 = (uv_offset + glyph->X + glyph->Width) * tex_scale_x;
-                const float t2 = (uv_offset + glyph->Y + glyph->Height) * tex_scale_y;
+                const float s1 = (glyph->X) * tex_scale_x;
+                const float t1 = (glyph->Y) * tex_scale_y;
+                const float s2 = (glyph->X + glyph->Width) * tex_scale_x;
+                const float t2 = (glyph->Y + glyph->Height) * tex_scale_y;
 
                 out_vertices[0].pos = ImVec2(x1, y1);
                 out_vertices[0].uv  = ImVec2(s1, t1);

imgui.h

@@ -391,7 +391,7 @@ struct ImGuiIO
     ImFont      Font;                       // <auto>                   // Gets passed to text functions. Typedef ImFont to the type you want (ImBitmapFont* or your own font).
     float       FontHeight;                 // <auto>                   // Default font height, must be the vertical distance between two lines of text, aka == CalcTextSize(" ").y
     bool        FontAllowScaling;           // = false                  // Set to allow scaling text with CTRL+Wheel.
-    float       PixelCenterOffset;          // = 0.5f                   // Set to 0.0f for DirectX <= 9, 0.5f for Direct3D >= 10 and OpenGL.
+    float       PixelCenterOffset;          // = 0.0f                   // Try to set to 0.5f or 0.375f if rendering is blurry
 
     // Settings - Rendering function (REQUIRED)
     // See example code if you are unsure of how to implement this.