mirror of
https://github.com/bloeys/nmage.git
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Complete engine game loop+abstract imgui
This commit is contained in:
bloeys
202
ui/imgui/imgui.go
Executable file
202
ui/imgui/imgui.go
Executable file
@ -0,0 +1,202 @@
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package nmageimgui
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import (
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"github.com/bloeys/gglm/gglm"
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"github.com/bloeys/nmage/asserts"
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"github.com/bloeys/nmage/materials"
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"github.com/bloeys/nmage/timing"
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"github.com/go-gl/gl/v4.1-core/gl"
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"github.com/inkyblackness/imgui-go/v4"
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"github.com/veandco/go-sdl2/sdl"
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)
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type ImguiInfo struct {
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ImCtx *imgui.Context
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Mat *materials.Material
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vaoID uint32
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vboID uint32
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indexBufID uint32
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texID uint32
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}
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func (i *ImguiInfo) FrameStart(winWidth, winHeight float32) {
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if err := i.ImCtx.SetCurrent(); err != nil {
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asserts.T(false, "Setting imgui ctx as current failed. Err: "+err.Error())
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}
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imIO := imgui.CurrentIO()
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imIO.SetDisplaySize(imgui.Vec2{X: float32(winWidth), Y: float32(winHeight)})
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// Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
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frequency := sdl.GetPerformanceFrequency()
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currentTime := sdl.GetPerformanceCounter()
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if timing.ElapsedTime() > 0 {
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imIO.SetDeltaTime(float32(currentTime-timing.ElapsedTime()) / float32(frequency))
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} else {
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imIO.SetDeltaTime(1.0 / 60.0)
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}
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imgui.NewFrame()
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}
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func (i *ImguiInfo) Render(winWidth, winHeight float32, fbWidth, fbHeight int32) {
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if err := i.ImCtx.SetCurrent(); err != nil {
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asserts.T(false, "Setting imgui ctx as current failed. Err: "+err.Error())
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}
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imgui.Render()
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// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
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if fbWidth <= 0 || fbHeight <= 0 {
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return
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}
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drawData := imgui.RenderedDrawData()
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drawData.ScaleClipRects(imgui.Vec2{
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X: float32(fbWidth) / float32(winWidth),
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Y: float32(fbHeight) / float32(winHeight),
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})
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// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
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gl.Enable(gl.BLEND)
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gl.BlendEquation(gl.FUNC_ADD)
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gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
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gl.Disable(gl.CULL_FACE)
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gl.Disable(gl.DEPTH_TEST)
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gl.Enable(gl.SCISSOR_TEST)
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gl.PolygonMode(gl.FRONT_AND_BACK, gl.FILL)
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// Setup viewport, orthographic projection matrix
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// Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
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// DisplayMin is typically (0,0) for single viewport apps.
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i.Mat.Bind()
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gl.Uniform1i(gl.GetUniformLocation(i.Mat.ShaderProg.ID, gl.Str("Texture\x00")), 0)
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//PERF: only update the ortho matrix on window resize
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orthoMat := gglm.Ortho(0, float32(winWidth), 0, float32(winHeight), 0, 20)
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i.Mat.SetUnifMat4("ProjMtx", &orthoMat.Mat4)
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gl.BindSampler(0, 0) // Rely on combined texture/sampler state.
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// Recreate the VAO every time
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// (This is to easily allow multiple GL contexts. VAO are not shared among GL contexts, and
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// we don't track creation/deletion of windows so we don't have an obvious key to use to cache them.)
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gl.BindVertexArray(i.vaoID)
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gl.BindBuffer(gl.ARRAY_BUFFER, i.vboID)
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vertexSize, vertexOffsetPos, vertexOffsetUv, vertexOffsetCol := imgui.VertexBufferLayout()
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i.Mat.EnableAttribute("Position")
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i.Mat.EnableAttribute("UV")
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i.Mat.EnableAttribute("Color")
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gl.VertexAttribPointerWithOffset(uint32(i.Mat.GetAttribLoc("Position")), 2, gl.FLOAT, false, int32(vertexSize), uintptr(vertexOffsetPos))
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gl.VertexAttribPointerWithOffset(uint32(i.Mat.GetAttribLoc("UV")), 2, gl.FLOAT, false, int32(vertexSize), uintptr(vertexOffsetUv))
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gl.VertexAttribPointerWithOffset(uint32(i.Mat.GetAttribLoc("Color")), 4, gl.UNSIGNED_BYTE, true, int32(vertexSize), uintptr(vertexOffsetCol))
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indexSize := imgui.IndexBufferLayout()
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drawType := gl.UNSIGNED_SHORT
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if indexSize == 4 {
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drawType = gl.UNSIGNED_INT
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}
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// Draw
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for _, list := range drawData.CommandLists() {
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vertexBuffer, vertexBufferSize := list.VertexBuffer()
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gl.BindBuffer(gl.ARRAY_BUFFER, i.vboID)
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gl.BufferData(gl.ARRAY_BUFFER, vertexBufferSize, vertexBuffer, gl.STREAM_DRAW)
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indexBuffer, indexBufferSize := list.IndexBuffer()
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gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, i.indexBufID)
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gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, indexBufferSize, indexBuffer, gl.STREAM_DRAW)
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for _, cmd := range list.Commands() {
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if cmd.HasUserCallback() {
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cmd.CallUserCallback(list)
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} else {
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gl.BindTexture(gl.TEXTURE_2D, i.texID)
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clipRect := cmd.ClipRect()
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gl.Scissor(int32(clipRect.X), int32(fbHeight)-int32(clipRect.W), int32(clipRect.Z-clipRect.X), int32(clipRect.W-clipRect.Y))
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gl.DrawElementsBaseVertex(gl.TRIANGLES, int32(cmd.ElementCount()), uint32(drawType), gl.PtrOffset(cmd.IndexOffset()*indexSize), int32(cmd.VertexOffset()))
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}
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}
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}
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//Reset gl state
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gl.Disable(gl.BLEND)
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gl.Disable(gl.SCISSOR_TEST)
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gl.Enable(gl.CULL_FACE)
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gl.Enable(gl.DEPTH_TEST)
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}
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func NewImGUI() ImguiInfo {
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imguiInfo := ImguiInfo{
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ImCtx: imgui.CreateContext(nil),
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Mat: materials.NewMaterial("ImGUI Mat", "./res/shaders/imgui"),
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}
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imIO := imgui.CurrentIO()
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imIO.SetBackendFlags(imIO.GetBackendFlags() | imgui.BackendFlagsRendererHasVtxOffset)
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gl.GenVertexArrays(1, &imguiInfo.vaoID)
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gl.GenBuffers(1, &imguiInfo.vboID)
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gl.GenBuffers(1, &imguiInfo.indexBufID)
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gl.GenTextures(1, &imguiInfo.texID)
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// Upload font to gpu
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gl.BindTexture(gl.TEXTURE_2D, imguiInfo.texID)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
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gl.PixelStorei(gl.UNPACK_ROW_LENGTH, 0)
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image := imIO.Fonts().TextureDataAlpha8()
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gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RED, int32(image.Width), int32(image.Height), 0, gl.RED, gl.UNSIGNED_BYTE, image.Pixels)
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// Store our identifier
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imIO.Fonts().SetTextureID(imgui.TextureID(imguiInfo.texID))
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//Shader attributes
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imguiInfo.Mat.Bind()
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imguiInfo.Mat.EnableAttribute("Position")
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imguiInfo.Mat.EnableAttribute("UV")
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imguiInfo.Mat.EnableAttribute("Color")
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imguiInfo.Mat.UnBind()
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//Init imgui input mapping
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keys := map[int]int{
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imgui.KeyTab: sdl.SCANCODE_TAB,
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imgui.KeyLeftArrow: sdl.SCANCODE_LEFT,
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imgui.KeyRightArrow: sdl.SCANCODE_RIGHT,
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imgui.KeyUpArrow: sdl.SCANCODE_UP,
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imgui.KeyDownArrow: sdl.SCANCODE_DOWN,
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imgui.KeyPageUp: sdl.SCANCODE_PAGEUP,
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imgui.KeyPageDown: sdl.SCANCODE_PAGEDOWN,
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imgui.KeyHome: sdl.SCANCODE_HOME,
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imgui.KeyEnd: sdl.SCANCODE_END,
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imgui.KeyInsert: sdl.SCANCODE_INSERT,
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imgui.KeyDelete: sdl.SCANCODE_DELETE,
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imgui.KeyBackspace: sdl.SCANCODE_BACKSPACE,
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imgui.KeySpace: sdl.SCANCODE_BACKSPACE,
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imgui.KeyEnter: sdl.SCANCODE_RETURN,
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imgui.KeyEscape: sdl.SCANCODE_ESCAPE,
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imgui.KeyA: sdl.SCANCODE_A,
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imgui.KeyC: sdl.SCANCODE_C,
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imgui.KeyV: sdl.SCANCODE_V,
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imgui.KeyX: sdl.SCANCODE_X,
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imgui.KeyY: sdl.SCANCODE_Y,
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imgui.KeyZ: sdl.SCANCODE_Z,
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}
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// Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
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for imguiKey, nativeKey := range keys {
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imIO.KeyMap(imguiKey, nativeKey)
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}
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return imguiInfo
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}
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