Added comments about requirement for bilinear filtering. (#5156, #3245)…

… + Backends: SDL_Renderer: Explicitely call SDL_SetTextureScaleMode(). (#4927)

backends/imgui_impl_allegro5.cpp

@@ -207,6 +207,7 @@ bool ImGui_ImplAllegro5_CreateDeviceObjects()
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
 
     // Create texture
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     int flags = al_get_new_bitmap_flags();
     int fmt = al_get_new_bitmap_format();
     al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP | ALLEGRO_MIN_LINEAR | ALLEGRO_MAG_LINEAR);

backends/imgui_impl_dx10.cpp

@@ -337,6 +337,7 @@ static void ImGui_ImplDX10_CreateFontsTexture()
     io.Fonts->SetTexID((ImTextureID)bd->pFontTextureView);
 
     // Create texture sampler
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     {
         D3D10_SAMPLER_DESC desc;
         ZeroMemory(&desc, sizeof(desc));

backends/imgui_impl_dx11.cpp

@@ -349,6 +349,7 @@ static void ImGui_ImplDX11_CreateFontsTexture()
     io.Fonts->SetTexID((ImTextureID)bd->pFontTextureView);
 
     // Create texture sampler
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     {
         D3D11_SAMPLER_DESC desc;
         ZeroMemory(&desc, sizeof(desc));

backends/imgui_impl_dx12.cpp

@@ -466,6 +466,7 @@ bool    ImGui_ImplDX12_CreateDeviceObjects()
         param[1].DescriptorTable.pDescriptorRanges = &descRange;
         param[1].ShaderVisibility = D3D12_SHADER_VISIBILITY_PIXEL;
 
+        // Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling.
         D3D12_STATIC_SAMPLER_DESC staticSampler = {};
         staticSampler.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
         staticSampler.AddressU = D3D12_TEXTURE_ADDRESS_MODE_WRAP;

backends/imgui_impl_dx9.cpp

@@ -84,7 +84,7 @@ static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
     vp.MaxZ = 1.0f;
     bd->pd3dDevice->SetViewport(&vp);
 
-    // Setup render state: fixed-pipeline, alpha-blending, no face culling, no depth testing, shade mode (for gradient)
+    // Setup render state: fixed-pipeline, alpha-blending, no face culling, no depth testing, shade mode (for gradient), bilinear sampling.
     bd->pd3dDevice->SetPixelShader(NULL);
     bd->pd3dDevice->SetVertexShader(NULL);
     bd->pd3dDevice->SetRenderState(D3DRS_FILLMODE, D3DFILL_SOLID);

backends/imgui_impl_metal.mm

@@ -350,6 +350,7 @@ - (void)enqueueReusableBuffer:(MetalBuffer *)buffer
     return renderPipelineState;
 }
 
+// Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling.
 - (id<MTLRenderPipelineState>)_renderPipelineStateForFramebufferDescriptor:(FramebufferDescriptor *)descriptor device:(id<MTLDevice>)device
 {
     NSError *error = nil;

backends/imgui_impl_opengl2.cpp

@@ -244,6 +244,7 @@ bool ImGui_ImplOpenGL2_CreateFontsTexture()
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
 
     // Upload texture to graphics system
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     GLint last_texture;
     glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
     glGenTextures(1, &bd->FontTexture);

backends/imgui_impl_opengl3.cpp

@@ -539,6 +539,7 @@ bool ImGui_ImplOpenGL3_CreateFontsTexture()
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
 
     // Upload texture to graphics system
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     GLint last_texture;
     glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
     glGenTextures(1, &bd->FontTexture);

backends/imgui_impl_sdlrenderer.cpp

@@ -210,6 +210,7 @@ bool ImGui_ImplSDLRenderer_CreateFontsTexture()
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
 
     // Upload texture to graphics system
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     bd->FontTexture = SDL_CreateTexture(bd->SDLRenderer, SDL_PIXELFORMAT_ABGR8888, SDL_TEXTUREACCESS_STATIC, width, height);
     if (bd->FontTexture == NULL)
     {
@@ -218,6 +219,7 @@ bool ImGui_ImplSDLRenderer_CreateFontsTexture()
     }
     SDL_UpdateTexture(bd->FontTexture, NULL, pixels, 4 * width);
     SDL_SetTextureBlendMode(bd->FontTexture, SDL_BLENDMODE_BLEND);
+    SDL_SetTextureScaleMode(bd->FontTexture, SDL_ScaleModeLinear);
 
     // Store our identifier
     io.Fonts->SetTexID((ImTextureID)(intptr_t)bd->FontTexture);

backends/imgui_impl_vulkan.cpp

@@ -741,6 +741,7 @@ static void ImGui_ImplVulkan_CreateFontSampler(VkDevice device, const VkAllocati
     if (bd->FontSampler)
         return;
 
+    // Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling.
     VkSamplerCreateInfo info = {};
     info.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
     info.magFilter = VK_FILTER_LINEAR;

backends/imgui_impl_wgpu.cpp

@@ -509,6 +509,7 @@ static void ImGui_ImplWGPU_CreateFontsTexture()
     }
 
     // Create the associated sampler
+    // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
     {
         WGPUSamplerDescriptor sampler_desc = {};
         sampler_desc.minFilter = WGPUFilterMode_Linear;

imgui.cpp

@@ -292,6 +292,7 @@ CODE
     void void MyImGuiRenderFunction(ImDrawData* draw_data)
     {
        // TODO: Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled
+       // TODO: Setup texture sampling state: sample with bilinear filtering (NOT point/nearest filtering). Use 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines;' to allow point/nearest filtering.
        // TODO: Setup viewport covering draw_data->DisplayPos to draw_data->DisplayPos + draw_data->DisplaySize
        // TODO: Setup orthographic projection matrix cover draw_data->DisplayPos to draw_data->DisplayPos + draw_data->DisplaySize
        // TODO: Setup shader: vertex { float2 pos, float2 uv, u32 color }, fragment shader sample color from 1 texture, multiply by vertex color.
@@ -1070,7 +1071,7 @@ ImGuiStyle::ImGuiStyle()
     DisplaySafeAreaPadding  = ImVec2(3,3);      // If you cannot see the edge of your screen (e.g. on a TV) increase the safe area padding. Covers popups/tooltips as well regular windows.
     MouseCursorScale        = 1.0f;             // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
     AntiAliasedLines        = true;             // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU.
-    AntiAliasedLinesUseTex  = true;             // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering.
+    AntiAliasedLinesUseTex  = true;             // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering (NOT point/nearest filtering).
     AntiAliasedFill         = true;             // Enable anti-aliased 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.
     CircleTessellationMaxError = 0.30f;         // 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.

imgui.h

@@ -1870,7 +1870,7 @@ struct ImGuiStyle
     ImVec2      DisplaySafeAreaPadding;     // If you cannot see the edges of your screen (e.g. on a TV) increase the safe area padding. Apply to popups/tooltips as well regular windows. NB: Prefer configuring your TV sets correctly!
     float       MouseCursorScale;           // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
     bool        AntiAliasedLines;           // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
-    bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering. Latched at the beginning of the frame (copied to ImDrawList).
+    bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering (NOT point/nearest filtering). Latched at the beginning of the frame (copied to ImDrawList).
     bool        AntiAliasedFill;            // Enable anti-aliased edges around filled shapes (rounded rectangles, circles, etc.). Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
     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       CircleTessellationMaxError; // 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.
@@ -2478,7 +2478,7 @@ enum ImDrawListFlags_
 {
     ImDrawListFlags_None                    = 0,
     ImDrawListFlags_AntiAliasedLines        = 1 << 0,  // Enable anti-aliased lines/borders (*2 the number of triangles for 1.0f wide line or lines thin enough to be drawn using textures, otherwise *3 the number of triangles)
-    ImDrawListFlags_AntiAliasedLinesUseTex  = 1 << 1,  // Enable anti-aliased lines/borders using textures when possible. Require backend to render with bilinear filtering.
+    ImDrawListFlags_AntiAliasedLinesUseTex  = 1 << 1,  // Enable anti-aliased lines/borders using textures when possible. Require backend to render with bilinear filtering (NOT point/nearest filtering).
     ImDrawListFlags_AntiAliasedFill         = 1 << 2,  // Enable anti-aliased edge around filled shapes (rounded rectangles, circles).
     ImDrawListFlags_AllowVtxOffset          = 1 << 3   // Can emit 'VtxOffset > 0' to allow large meshes. Set when 'ImGuiBackendFlags_RendererHasVtxOffset' is enabled.
 };
@@ -2716,7 +2716,7 @@ enum ImFontAtlasFlags_
     ImFontAtlasFlags_None               = 0,
     ImFontAtlasFlags_NoPowerOfTwoHeight = 1 << 0,   // Don't round the height to next power of two
     ImFontAtlasFlags_NoMouseCursors     = 1 << 1,   // Don't build software mouse cursors into the atlas (save a little texture memory)
-    ImFontAtlasFlags_NoBakedLines       = 1 << 2    // Don't build thick line textures into the atlas (save a little texture memory). The AntiAliasedLinesUseTex features uses them, otherwise they will be rendered using polygons (more expensive for CPU/GPU).
+    ImFontAtlasFlags_NoBakedLines       = 1 << 2    // Don't build thick line textures into the atlas (save a little texture memory, allow support for point/nearest filtering). The AntiAliasedLinesUseTex features uses them, otherwise they will be rendered using polygons (more expensive for CPU/GPU).
 };
 
 // Load and rasterize multiple TTF/OTF fonts into a same texture. The font atlas will build a single texture holding:
@@ -2804,7 +2804,7 @@ struct ImFontAtlas
     ImFontAtlasFlags            Flags;              // Build flags (see ImFontAtlasFlags_)
     ImTextureID                 TexID;              // User data to refer to the texture once it has been uploaded to user's graphic systems. It is passed back to you during rendering via the ImDrawCmd structure.
     int                         TexDesiredWidth;    // Texture width desired by user before Build(). Must be a power-of-two. If have many glyphs your graphics API have texture size restrictions you may want to increase texture width to decrease height.
-    int                         TexGlyphPadding;    // Padding between glyphs within texture in pixels. Defaults to 1. If your rendering method doesn't rely on bilinear filtering you may set this to 0.
+    int                         TexGlyphPadding;    // Padding between glyphs within texture in pixels. Defaults to 1. If your rendering method doesn't rely on bilinear filtering you may set this to 0 (will also need to set AntiAliasedLinesUseTex = false).
     bool                        Locked;             // Marked as Locked by ImGui::NewFrame() so attempt to modify the atlas will assert.
 
     // [Internal]