Backends: SDLGPU3: Added sdl_gpu backend. (ocornut#8163, ocornut#7998, …

…ocornut#7988)

+Squashed: Optimized shader source code encoding by ocornut (ocornut#8163, ocornut#7998, ocornut#7988)
(squashed to avoid storing both in git history, 130 KB->62 KB)

backends/imgui_impl_sdlgpu3.h

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+// dear imgui: Renderer Backend for SDL_Gpu
+// This needs to be used along with the SDL3 Platform Backend
+
+// Implemented features:
+//  [X] Renderer: User texture binding. Use simply cast a reference to your SDL_GPUTextureSamplerBinding to ImTextureID.
+//  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.
+
+// The aim of imgui_impl_sdlgpu3.h/.cpp is to be usable in your engine without any modification.
+// IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
+
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
+// Learn about Dear ImGui:
+// - FAQ                  https://dearimgui.com/faq
+// - Getting Started      https://dearimgui.com/getting-started
+// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
+// - Introduction, links and more at the top of imgui.cpp
+
+// Important note to the reader who wish to integrate imgui_impl_sdlgpu3.cpp/.h in their own engine/app.
+// - Unline other backends, the user must call the function Imgui_ImplSDLGPU_PrepareDrawData BEFORE issuing a SDL_GPURenderPass containing ImGui_ImplSDLGPU_RenderDrawData.
+//   Calling the function is MANDATORY, otherwise the ImGui will not upload neither the vertex nor the index buffer for the GPU. See imgui_impl_sdlgpu3.cpp for more info.
+
+#pragma once
+#include "imgui.h"      // IMGUI_IMPL_API
+#ifndef IMGUI_DISABLE
+#include <SDL3/SDL_gpu.h>
+
+// Initialization data, for ImGui_ImplSDLGPU_Init()
+// - Remember to set ColorTargetFormat to the correct format. If you're rendering to the swapchain, call SDL_GetGPUSwapchainTextureFormat to query the right value
+struct ImGui_ImplSDLGPU_InitInfo
+{
+    SDL_GPUDevice*       GpuDevice          = nullptr;
+    SDL_GPUTextureFormat ColorTargetFormat  = SDL_GPU_TEXTUREFORMAT_INVALID;
+    SDL_GPUSampleCount   MSAASamples        = SDL_GPU_SAMPLECOUNT_1;
+};
+
+// Follow "Getting Started" link and check examples/ folder to learn about using backends!
+IMGUI_IMPL_API bool             ImGui_ImplSDLGPU_Init(ImGui_ImplSDLGPU_InitInfo* info);
+IMGUI_IMPL_API void             ImGui_ImplSDLGPU_Shutdown();
+IMGUI_IMPL_API void             ImGui_ImplSDLGPU_NewFrame();
+IMGUI_IMPL_API void             Imgui_ImplSDLGPU_PrepareDrawData(ImDrawData* draw_data, SDL_GPUCommandBuffer* command_buffer);
+IMGUI_IMPL_API void             ImGui_ImplSDLGPU_RenderDrawData(ImDrawData* draw_data, SDL_GPUCommandBuffer* command_buffer, SDL_GPURenderPass* render_pass, SDL_GPUGraphicsPipeline* pipeline = nullptr);
+IMGUI_IMPL_API bool             ImGui_ImplSDLGPU_CreateFontsTexture();
+IMGUI_IMPL_API void             ImGui_ImplSDLGPU_DestroyFontsTexture();
+
+#endif // #ifndef IMGUI_DISABLE

backends/sdlgpu3/build_instructions.txt

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+1) Compile the raw shader files to SPIRV:
+
+    glslc -o vertex.spv -c shader.vert
+    glslc -o fragment.spv -c shader.frag
+
+
+2) Build SDL_shadercross (https://github.com/libsdl-org/SDL_shadercross)
+
+
+3-A) Compiling for the Vulkan Driver:
+
+    Nothing to do, you just need the previous vertex.spv/fragment.spv, proceed to step 4
+
+
+3-B) Compiling for the DirectX 12 Driver:
+
+    ./shadercross vertex.spv -s SPIRV -d DXBC -t vertex -e main -o vertex.dxbc
+    ./shadercross fragment.spv -s SPIRV -d DXBC -t fragment -e main -o fragment.dxbc
+
+    Proceed to step 4
+
+
+3-C) Compiling for Metal (On windows you'll need the Metal Developer Tools for Windows, on linux you might use wine, but I never tested it):
+
+    ./shadercross vertex.spv -s SPIRV -d MSL -t vertex -e main -o vertex.metal
+    ./shadercross fragment.spv -s SPIRV -d MSL -t fragment -e main -o fragment.metal
+
+    xcrun -sdk macosx metal -o vertex.ir -c vertex.metal
+    xcrun -sdk macosx metal -o fragment.ir -c fragment.metal
+    xcrun -sdk macosx metallib -o vertex.metallib -c vertex.ir
+    xcrun -sdk macosx metallib -o fragment.metallib -c fragment.ir
+
+    Proceed to step 4
+
+
+4) Either find a way to load the shader bytecode from file, or use a tool like https://notisrac.github.io/FileToCArray/ to convert the file to a uint8_t array

backends/sdlgpu3/shader.frag

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+#version 450 core
+layout(location = 0) out vec4 fColor;
+
+layout(set=2, binding=0) uniform sampler2D sTexture;
+
+layout(location = 0) in struct {
+    vec4 Color;
+    vec2 UV;
+} In;
+
+void main()
+{
+    fColor = In.Color * texture(sTexture, In.UV.st);
+}

backends/sdlgpu3/shader.vert

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+#version 450 core
+layout(location = 0) in vec2 aPos;
+layout(location = 1) in vec2 aUV;
+layout(location = 2) in vec4 aColor;
+
+layout(set=1,binding=0) uniform UBO {
+    vec2 uScale;
+    vec2 uTranslate;
+} ubo;
+
+layout(location = 0) out struct {
+    vec4 Color;
+    vec2 UV;
+} Out;
+
+void main()
+{
+    Out.Color = aColor;
+    Out.UV = aUV;
+    gl_Position = vec4(aPos * ubo.uScale + ubo.uTranslate, 0, 1);
+    gl_Position.y *= -1.0f;
+}

examples/example_sdl3_sdlgpu3/Makefile

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+#
+# Cross Platform Makefile
+# Compatible with MSYS2/MINGW, Ubuntu 14.04.1 and Mac OS X
+#
+# You will need SDL3 (http://www.libsdl.org) which is still unreleased/unpackaged.
+
+#CXX = g++
+#CXX = clang++
+
+EXE = example_sdl3_sdlgpu3
+IMGUI_DIR = ../..
+SOURCES = main.cpp
+SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_tables.cpp $(IMGUI_DIR)/imgui_widgets.cpp
+SOURCES += $(IMGUI_DIR)/backends/imgui_impl_sdl3.cpp $(IMGUI_DIR)/backends/imgui_impl_sdlgpu3.cpp
+OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
+UNAME_S := $(shell uname -s)
+
+CXXFLAGS = -std=c++11 -I$(IMGUI_DIR) -I$(IMGUI_DIR)/backends
+CXXFLAGS += -g -Wall -Wformat
+LIBS =
+
+
+##---------------------------------------------------------------------
+## BUILD FLAGS PER PLATFORM
+##---------------------------------------------------------------------
+
+ifeq ($(UNAME_S), Linux) #LINUX
+	ECHO_MESSAGE = "Linux"
+	LIBS += -ldl `pkg-config sdl3 --libs`
+
+	CXXFLAGS += `pkg-config sdl3 --cflags`
+	CFLAGS = $(CXXFLAGS)
+endif
+
+ifeq ($(UNAME_S), Darwin) #APPLE
+	ECHO_MESSAGE = "Mac OS X"
+	LIBS += -framework Cocoa -framework IOKit -framework CoreVideo `pkg-config --libs sdl3`
+	LIBS += -L/usr/local/lib -L/opt/local/lib
+
+	CXXFLAGS += `pkg-config sdl3 --cflags`
+	CXXFLAGS += -I/usr/local/include -I/opt/local/include
+	CFLAGS = $(CXXFLAGS)
+endif
+
+ifeq ($(OS), Windows_NT)
+    ECHO_MESSAGE = "MinGW"
+    LIBS += -lgdi32 -limm32 `pkg-config --static --libs sdl3`
+
+    CXXFLAGS += `pkg-config --cflags sdl3`
+    CFLAGS = $(CXXFLAGS)
+endif
+
+##---------------------------------------------------------------------
+## BUILD RULES
+##---------------------------------------------------------------------
+
+%.o:%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/backends/%.cpp
+	$(CXX) $(CXXFLAGS) -c -o $@ $<
+
+all: $(EXE)
+	@echo Build complete for $(ECHO_MESSAGE)
+
+$(EXE): $(OBJS)
+	$(CXX) -o $@ $^ $(CXXFLAGS) $(LIBS)
+
+clean:
+	rm -f $(EXE) $(OBJS)

examples/example_sdl3_sdlgpu3/build_win64.bat

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+@REM Build for Visual Studio compiler. Run your copy of vcvars64.bat or vcvarsall.bat to setup command-line compiler.
+
+@set OUT_EXE=example_sdl3_sdlgpu3
+@set INCLUDES=/I..\.. /I..\..\backends /I%SDL3_DIR%\include
+@set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl3.cpp ..\..\backends\imgui_impl_sdlgpu3.cpp ..\..\imgui*.cpp
+@set LIBS=/LIBPATH:%SDL3_DIR%\lib\x64 SDL3.lib shell32.lib
+
+@set OUT_DIR=Debug
+mkdir %OUT_DIR%
+cl /nologo /Zi /MD /utf-8 %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console
+
+@set OUT_DIR=Release
+@REM mkdir %OUT_DIR%
+@REM cl /nologo /Zi /MD /utf-8 /Ox /Oi %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console