Files
SDL3-TestingSuite/SDL3/ImGuiSDL3Renderer.cs
2026-05-18 01:36:55 -05:00

371 lines
13 KiB
C#

using System.Numerics;
using System.Runtime.InteropServices;
using ImGuiNET;
using SDL3;
namespace SDL3_TestingSuite.SDL3;
/// <summary>
/// Implementation of ImGui for SDL3 Renderer backend.
/// https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_sdlrenderer3.h
/// </summary>
public unsafe static class ImGuiSDL3Renderer
{
public class RendererData
{
public nint Renderer; // Main viewport's renderer
public ImVector<SDL.FColor> ColorBuffer;
// Render State
public SDL.ScaleMode CurrentScaleMode;
}
private struct BackupSDLRendererState
{
public SDL.Rect Viewport;
public bool ViewportEnabled;
public bool ClipEnabled;
public SDL.Rect ClipRect;
}
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void RendererCreateWindowFn(ImGuiViewportPtr viewport);
private static readonly RendererCreateWindowFn RendererCreateWindowDelegate = RendererCreateWindow;
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void RendererDestroyWindowFn(ImGuiViewportPtr viewport);
private static readonly RendererDestroyWindowFn RendererDestroyWindowDelegate = RendererDestroyWindow;
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void RendererSetWindowSizeFn(ImGuiViewportPtr viewport, Vector2 size);
private static readonly RendererSetWindowSizeFn RendererSetWindowSizeDelegate = RendererSetWindowSize;
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void RendererRenderWindowFn(ImGuiViewportPtr viewport);
private static readonly RendererRenderWindowFn RendererRenderWindowDelegate = RendererRenderWindow;
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate void RendererSwapBuffersFn(ImGuiViewportPtr viewport);
private static readonly RendererSwapBuffersFn RendererSwapBuffersDelegate = RendererSwapBuffers;
public static RendererData Data => ImGui.GetCurrentContext() != nint.Zero ? ImGuiUserData<RendererData>.Get(ImGui.GetIO().BackendRendererUserData)! : null!;
private static nint _fontTexture = nint.Zero;
public static bool Init(nint renderer)
{
ImGuiIOPtr io = ImGui.GetIO();
RendererData bd = new RendererData();
io.BackendRendererUserData = ImGuiUserData<RendererData>.Store(bd);
io.BackendFlags |= ImGuiBackendFlags.RendererHasVtxOffset; // We can honor the ImDrawCmd.VtxOffset field, allowing for large meshes.
io.BackendFlags |= ImGuiBackendFlags.RendererHasViewports;
bd.Renderer = renderer;
ImGuiPlatformIOPtr platformIO = ImGui.GetPlatformIO();
platformIO.Renderer_CreateWindow = Marshal.GetFunctionPointerForDelegate(RendererCreateWindowDelegate);
platformIO.Renderer_DestroyWindow = Marshal.GetFunctionPointerForDelegate(RendererDestroyWindowDelegate);
platformIO.Renderer_SetWindowSize = Marshal.GetFunctionPointerForDelegate(RendererSetWindowSizeDelegate);
platformIO.Renderer_RenderWindow = Marshal.GetFunctionPointerForDelegate(RendererRenderWindowDelegate);
platformIO.Renderer_SwapBuffers = Marshal.GetFunctionPointerForDelegate(RendererSwapBuffersDelegate);
return true;
}
public static void Dispose()
{
var io = ImGui.GetIO();
var platformIO = ImGui.GetPlatformIO();
DestroyDeviceObjects();
io.BackendRendererUserData = nint.Zero;
io.BackendFlags &= ~ImGuiBackendFlags.RendererHasVtxOffset;
platformIO.Renderer_RenderState = nint.Zero;
platformIO.Renderer_CreateWindow = nint.Zero;
platformIO.Renderer_DestroyWindow = nint.Zero;
platformIO.Renderer_SetWindowSize = nint.Zero;
platformIO.Renderer_RenderWindow = nint.Zero;
platformIO.Renderer_SwapBuffers = nint.Zero;
}
public static void NewFrame()
{
if (_fontTexture == nint.Zero)
{
CreateDeviceObjects();
}
}
private static void RendererCreateWindow(ImGuiViewportPtr viewport)
{
Program.Logger.Log(null);
ImGuiSDL3Platform.ViewPortData? vd = ImGuiUserData<ImGuiSDL3Platform.ViewPortData>.Get(viewport.PlatformUserData);
if (vd == null || vd.Window == nint.Zero)
return;
if (vd.Renderer == nint.Zero)
{
vd.Renderer = SDL.CreateRenderer(vd.Window, (string?)null);
vd.RendererOwned = true;
}
Program.Logger.Log(null);
}
private static void RendererDestroyWindow(ImGuiViewportPtr viewport)
{
Program.Logger.Log(null);
ImGuiSDL3Platform.ViewPortData? vd = ImGuiUserData<ImGuiSDL3Platform.ViewPortData>.Get(viewport.PlatformUserData);
if (vd == null)
return;
if (vd.RendererOwned && vd.Renderer != nint.Zero)
{
SDL.DestroyRenderer(vd.Renderer);
}
vd.Renderer = nint.Zero;
vd.RendererOwned = false;
Program.Logger.Log(null);
}
private static void RendererSetWindowSize(ImGuiViewportPtr viewport, Vector2 size)
{
// SDL renderer windows track size through the platform window callback.
Program.Logger.Log(null);
}
private static void RendererRenderWindow(ImGuiViewportPtr viewport)
{
Program.Logger.Log(null);
ImGuiSDL3Platform.ViewPortData? vd = ImGuiUserData<ImGuiSDL3Platform.ViewPortData>.Get(viewport.PlatformUserData);
if (vd == null || vd.Renderer == nint.Zero)
{
return;
}
RenderDrawData(viewport.DrawData, vd.Renderer);
Program.Logger.Log(null);
}
private static void RendererSwapBuffers(ImGuiViewportPtr viewport)
{
Program.Logger.Log(null);
ImGuiSDL3Platform.ViewPortData? vd = ImGuiUserData<ImGuiSDL3Platform.ViewPortData>.Get(viewport.PlatformUserData);
if (vd == null || vd.Renderer == nint.Zero)
return;
SDL.RenderPresent(vd.Renderer);
Program.Logger.Log(null);
}
public static void RenderDrawData(ImDrawDataPtr drawData, nint renderer)
{
// Skip if no data to render
if (drawData.NativePtr == null || drawData.CmdListsCount == 0)
return;
SDL.GetRenderScale(renderer, out float renderScaleX, out float renderScaleY);
Vector2 renderScale = new Vector2(
renderScaleX == 1.0f ? drawData.FramebufferScale.X : 1.0f,
renderScaleY == 1.0f ? drawData.FramebufferScale.Y : 1.0f);
int fbWidth = (int)(drawData.DisplaySize.X * renderScale.X);
int fbHeight = (int)(drawData.DisplaySize.Y * renderScale.Y);
if (fbWidth <= 0 || fbHeight <= 0)
return;
// Backup SDL renderer state
BackupSDLRendererState old = new BackupSDLRendererState
{
ViewportEnabled = SDL.RenderViewportSet(renderer),
ClipEnabled = SDL.RenderClipEnabled(renderer)
};
SDL.GetRenderViewport(renderer, out var oldViewport);
old.Viewport = oldViewport;
SDL.GetRenderClipRect(renderer, out var oldClipRect);
old.ClipRect = oldClipRect;
// Set up render state
SDL.SetRenderViewport(renderer, 0);
SDL.SetRenderClipRect(renderer, nint.Zero);
// Set render state in platform IO
ImGuiPlatformIOPtr platformIo = ImGui.GetPlatformIO();
platformIo.Renderer_RenderState = renderer;
Vector2 clipOffset = drawData.DisplayPos;
// Render command lists
for (int n = 0; n < drawData.CmdListsCount; n++)
{
ImDrawListPtr cmdList = drawData.CmdLists[n];
for (int cmdIndex = 0; cmdIndex < cmdList.CmdBuffer.Size; cmdIndex++)
{
ImDrawCmdPtr cmd = cmdList.CmdBuffer[cmdIndex];
if (cmd.UserCallback != nint.Zero)
{
continue; // User callback not implemented
}
// Apply clipping rectangle
Vector4 clipRect = cmd.ClipRect;
Vector2 clipMin = new Vector2((clipRect.X - clipOffset.X) * renderScale.X, (clipRect.Y - clipOffset.Y) * renderScale.Y);
Vector2 clipMax = new Vector2((clipRect.Z - clipOffset.X) * renderScale.X, (clipRect.W - clipOffset.Y) * renderScale.Y);
clipMin.X = Math.Max(0, clipMin.X);
clipMin.Y = Math.Max(0, clipMin.Y);
clipMax.X = Math.Min(fbWidth, clipMax.X);
clipMax.Y = Math.Min(fbHeight, clipMax.Y);
if (clipMax.X <= clipMin.X || clipMax.Y <= clipMin.Y)
continue;
SDL.Rect r = new SDL.Rect
{
X = (int)clipMin.X,
Y = (int)clipMin.Y,
W = (int)(clipMax.X - clipMin.X),
H = (int)(clipMax.Y - clipMin.Y)
};
SDL.SetRenderClipRect(renderer, r);
// Get texture
nint texId = cmd.GetTexID();
// Convert ImGui vertices to SDL vertices
if (!RenderDrawCommand(cmdList, cmd, renderer, texId, renderScale))
{
Console.WriteLine($"Failed to render ImGui draw command: {SDL.GetError()}");
}
}
}
// Reset render state
platformIo.Renderer_RenderState = nint.Zero;
// Restore renderer state
SDL.SetRenderViewport(renderer, old.ViewportEnabled ? old.Viewport : new SDL.Rect());
SDL.SetRenderClipRect(renderer, old.ClipEnabled ? old.ClipRect : new SDL.Rect());
}
private static bool RenderDrawCommand(ImDrawListPtr drawList, ImDrawCmdPtr cmd, nint renderer, nint texId, Vector2 scale)
{
uint indexOffset = cmd.IdxOffset;
uint vertexOffset = cmd.VtxOffset;
uint elemCount = cmd.ElemCount;
SDL.Vertex[] vertices = new SDL.Vertex[elemCount];
int[] indices = new int[elemCount];
for (int i = 0; i < elemCount; i++)
{
ushort idx = drawList.IdxBuffer[(int)indexOffset + i];
int vertIdx = (int)(vertexOffset + idx);
ImDrawVertPtr srcVert = drawList.VtxBuffer[vertIdx];
uint col = srcVert.col;
byte r = (byte)((col >> 0) & 0xFF);
byte g = (byte)((col >> 8) & 0xFF);
byte b = (byte)((col >> 16) & 0xFF);
byte a = (byte)((col >> 24) & 0xFF);
vertices[i] = new SDL.Vertex()
{
Position = new SDL.FPoint()
{
X = srcVert.pos.X * scale.X,
Y = srcVert.pos.Y * scale.Y
},
Color = new SDL.FColor()
{
R = r / 255f,
G = g / 255f,
B = b / 255f,
A = a / 255f
},
TexCoord = new SDL.FPoint()
{
X = srcVert.uv.X,
Y = srcVert.uv.Y
}
};
indices[i] = i;
}
return SDL.RenderGeometry(renderer, texId, vertices, vertices.Length, indices, indices.Length);
}
public static void CreateDeviceObjects()
{
ImGuiIOPtr io = ImGui.GetIO();
var data = Data;
io.Fonts.AddFontDefault();
// TODO: Load custom fonts from "Fonts" directory
//string fontsPath = Path.Combine(Plugin.AssemblyDirectory, "Fonts");
//if (Path.Exists(fontsPath))
//{
// string[] fonts = Directory.GetFiles(fontsPath, "*.ttf");
// if (fonts.Length > 0)
// {
// foreach (string font in fonts)
// {
// io.Fonts.AddFontFromFileTTF(font, 20f);
// }
// }
//}
// Build texture atlas
io.Fonts.GetTexDataAsRGBA32(out byte* pixels, out int width, out int height);
// Create surface from pixel data
nint surface = SDL.CreateSurfaceFrom(width, height, SDL.PixelFormat.RGBA8888, (nint)pixels, width * 4);
if (surface == nint.Zero)
{
SDL.LogError(SDL.LogCategory.Application, $"Failed to create font surface: {SDL.GetError()}");
return;
}
// Create texture
_fontTexture = SDL.CreateTextureFromSurface(data.Renderer, surface);
if (_fontTexture == nint.Zero)
{
SDL.LogError(SDL.LogCategory.Application, $"Failed to create font texture: {SDL.GetError()}");
return;
}
// Update texture directly without converting pixel format
if (!SDL.UpdateTexture(_fontTexture, nint.Zero, (nint)pixels, width * 4))
{
SDL.LogError(SDL.LogCategory.Application, $"Failed to update font texture: {SDL.GetError()}");
return;
}
// Ensure proper blending for font rendering
SDL.SetTextureBlendMode(_fontTexture, SDL.BlendMode.Blend);
// Use nearest neighbor filtering for crisp font rendering at small sizes
SDL.SetTextureScaleMode(_fontTexture, SDL.ScaleMode.Linear);
// Store our identifier
io.Fonts.SetTexID(_fontTexture);
SDL.DestroySurface(surface);
io.Fonts.ClearTexData();
}
public static void DestroyDeviceObjects() { }
}