Add sdl_gpu demo, add more glyph positions and text rendering

examples/demo_sdl2_gpu.nim

@@ -0,0 +1,156 @@
+import sdl2 as sdl
+import sdl2/sdl2_gpu as gpu
+import opengl
+
+import os
+import nanovg
+import perf
+import common
+
+proc events(): bool =
+  result = false
+  var e: sdl.Event
+
+  while sdl.pollEvent(addr(e)) != 0:
+
+    # Quit requested
+    if e.kind.EventType == sdl.EventQuit:
+      return true
+
+    # Key pressed
+    elif e.kind.EventType == sdl.EventKeyDown:
+      # Exit on Escape key press
+      if e.key.keysym.sym == sdl.KeycodeEscape:
+        return true
+
+proc frameBufferSize*(window: ptr Window): tuple[w, h: int32] =
+  var
+    fbWidth: cint
+    fbHeight: cint
+
+  window.glGetDrawableSize(fbWidth.addr, fbHeight.addr)
+
+  return (fbWidth.int32, fbHeight.int32)
+
+proc size*(window: ptr Window): tuple[w, h: int32] =
+  var
+    width: cint
+    height: cint
+
+  window.getWindowSize(width.addr, height.addr)
+
+  return (width.int32, height.int32)
+
+template generateFbo(width, height: float, code: untyped): gpu.Image =
+  let fb = createFrameBuffer(width, height, ImageFlagsGL.NO_DELETE)
+  fb.binde()
+
+  glViewPort(0, 0, width.int, height.int)
+  glCullFace(GL_BACK)
+  glFrontFace(GL_CCW)
+  glClearColor(0.3, 0.3, 0.32, 1.0)
+  glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT)
+  beginFrame(width, height, 1.0)
+  code
+  endFrame()
+  gpu.resetRendererState()
+  echo fb.texture
+  let res = gpu.createImageUsingTexture(cast[TextureHandle](fb.texture), false)
+  fb.delete()
+  res
+
+proc windowID*(target: ptr Target): uint32 {.
+    cdecl, importc: "GPU_getWindowID".}
+
+proc main() =
+  let
+    fps = newGraph(RenderStyle.FPS, "Frame Time")
+    cpuGraph = newGraph(RenderStyle.MS, "CPU Time")
+
+  discard sdl.init(sdl.INIT_EVERYTHING.uint32)
+  discard sdl.glSetAttribute(sdl.GL_STENCIL_SIZE, 1)
+  discard sdl.glSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE.cint)
+  discard sdl.glSetAttribute(sdl.GL_CONTEXT_FLAGS, sdl.GL_CONTEXT_FORWARD_COMPATIBLE_FLAG.cint)
+  discard sdl.glSetAttribute(sdl.GL_CONTEXT_MAJOR_VERSION, 3)
+  discard sdl.glSetAttribute(sdl.GL_CONTEXT_MINOR_VERSION, 2)
+  var w, h: cint
+
+  # let
+  #   vert = gpu.loadShader(gpu.VERTEX_SHADER, currentSourceDir()/"resources/untextured.vert")
+  #   frag = gpu.loadShader(gpu.FRAGMENT_SHADER, currentSourceDir()/"resources/untextured.frag")
+  #   program = gpu.linkShaders(vert, frag)
+
+  # glUseProgram(program)
+
+  # let
+  #   vertLoc = gpu.getAttributeLocation(program, "gpu_Vertex")
+  #   colorLoc = gpu.getAttributeLocation(program, "gpu_Color")
+  #   mvpLoc = gpu.getUniformLocation(program, "gpu_ModelViewProjectionMatrix")
+
+  let screen = gpu.initRenderer(gpu.RENDERER_OPENGL_3, 640, 480, sdl.WINDOW_ALLOW_HIGHDPI)
+  gpu.setRequiredFeatures(gpu.FEATURE_BASIC_SHADERS)
+
+
+  nanovg.init()
+  discard sdl.glSetSwapInterval(0)
+  nanovg.loadFont(currentSourceDir()/"resources/Roboto-Regular.ttf", "sans")
+  nanovg.loadFont(currentSourceDir()/"resources/Roboto-Bold.ttf", "sans-bold")
+  nanovg.loadFont(currentSourceDir()/"resources/fa.ttf", "fa")
+  nanovg.loadFont(currentSourceDir()/"resources/entypo.ttf", "icons")
+
+  var done = false
+  var prevt: float = sdl.getTicks().float/1000.0
+
+  var image = gpu.loadImage(currentSourceDir()/"resources/howl.png")
+
+  let window = sdl.getWindowFromID(screen.context.windowID)
+
+  while not done:
+    gpu.clearRGBA(screen, 0, 0, 0, 0xFF)
+
+    # do gpu drawing
+
+    let fbSize = window.frameBufferSize()
+
+    glViewPort(0, 0, fbSize.w, fbSize.h)
+    glCullFace(GL_BACK)
+    glFrontFace(GL_CCW)
+    glClearColor(0.3, 0.3, 0.32, 1.0)
+    glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT)
+
+    gpu.blit(image, nil, screen, 400, 100)
+
+    gpu.flushBlitBuffer()
+
+    withFrame(window):
+      let x = glyphPositions("Some仮名thing is up", 0, 0, 10)
+      echo x
+      text("Some仮名thing is up", 100, 100, 100)
+      drawWindow("Title", 50, 50, 300, 400)
+      drawLabel("Hello!", 10, 10, 500, 20)
+      drawButton(ICON_TRASH, "Delete", 100, 200, 160, 28, RGBA(128, 16, 8, 255))
+      drawButton(ICON_TRASH, "Deleter", 100, 250, 160, 28, RGBA(12, 130, 80, 255))
+      drawButton("Testing", 100, 300, 160, 28)
+
+    gpu.resetRendererState()
+
+    fps.render(5, 5)
+    cpuGraph.render(210, 5)
+
+
+    gpu.flip(screen)
+
+    let t: float = sdl.getTicks().float/1000.0
+    let dt = t - prevt
+    prevt = t
+
+    let cpuTime: float = sdl.getTicks().float/1000.0 - t
+
+    fps.update(dt)
+    cpuGraph.update(cpuTime)
+
+    done = events()
+  gpu.freeImage(image)
+  gpu.quit()
+
+main()