1 files changed, 363 insertions, 0 deletions
diff --git a/src/fw/opengl.odin b/src/fw/opengl.odin
new file mode 100644
index 0000000..ab2bb81
--- /dev/null
+++ b/src/fw/opengl.odin
@@ -0,0 +1,363 @@
+package fw
+
+import "base:runtime"
+
+import "core:log"
+import "core:fmt"
+import "core:math/linalg"
+import "core:os"
+
+import "vendor:glfw"
+import gl "vendor:OpenGL"
+
+@(private)
+enum_conv: map[All_Enums]u32
+
+vert_shader_src := string(#load("shader.vert"))
+frag_shader_src := string(#load("shader.frag"))
+
+vao: u32
+vbo: u32
+ebo: u32
+
+framebuf: struct {
+  handle: u32,
+  color: Texture, // so we can reuse pre-existing draw procs
+  depth: u32,
+}
+shader_program: u32
+
+projection_loc: i32
+view_loc: i32
+tex0_loc: i32
+
+// @(private)
+// _gl_debug_message :: proc "c" (
+//   source: u32,
+//   type: u32,
+//   id: u32,
+//   severity: u32,
+//   length: i32,
+//   message: cstring,
+//   userParam: rawptr,
+// ) {
+//   context = runtime.default_context()
+//   switch severity {
+//   case gl.DEBUG_SEVERITY_HIGH: fmt.print("[HIGH]")
+//   case gl.DEBUG_SEVERITY_MEDIUM: fmt.print("[MEDIUM]")
+//   case gl.DEBUG_SEVERITY_LOW: fmt.print("[LOW]")
+//   case gl.DEBUG_SEVERITY_NOTIFICATION: fmt.print("[NOTIF]")
+//   }
+//   fmt.printfln(" OpenGL %v: %v", id, message)
+// }
+
+@(private)
+_init_vertex_buffer_and_array :: proc(vao: u32, vbo: u32, ebo: u32) {
+  gl.BindVertexArray(vao)
+
+  gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
+  gl.BufferData(gl.ARRAY_BUFFER, 0, nil, gl.DYNAMIC_DRAW)
+
+  gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo)
+  gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, 0, nil, gl.DYNAMIC_DRAW)
+
+  stride := i32(size_of(Vertex))
+
+  gl.EnableVertexAttribArray(0)
+  gl.VertexAttribPointer(0, 3, gl.FLOAT, false, stride, offset_of(Vertex, pos))
+
+  gl.EnableVertexAttribArray(1)
+  gl.VertexAttribPointer(1, 2, gl.FLOAT, false, stride, offset_of(Vertex, uv))
+
+  gl.EnableVertexAttribArray(2)
+  gl.VertexAttribPointer(
+    2,
+    4,
+    gl.FLOAT,
+    false,
+    stride,
+    offset_of(Vertex, color),
+  )
+}
+
+@(private)
+_gl_load_shader :: proc(src: string, type: u32) -> u32 {
+  shader := gl.CreateShader(type)
+  csrc := cstring(raw_data(src))
+  src_len := i32(len(src))
+  gl.ShaderSource(shader, 1, &csrc, &src_len)
+  gl.CompileShader(shader)
+
+  status: i32
+  gl.GetShaderiv(shader, gl.COMPILE_STATUS, &status)
+  if status == 0 {
+    gl.DeleteShader(shader)
+    return 0
+  }
+
+  return shader
+}
+
+@(private)
+_gl_load_shader_program :: proc(vert_src: string, frag_src: string) -> u32 {
+  vert_shader := _gl_load_shader(vert_src, gl.VERTEX_SHADER)
+  defer gl.DeleteShader(vert_shader)
+  frag_shader := _gl_load_shader(frag_src, gl.FRAGMENT_SHADER)
+  defer gl.DeleteShader(frag_shader)
+
+  program := gl.CreateProgram()
+  gl.AttachShader(program, vert_shader)
+  gl.AttachShader(program, frag_shader)
+  gl.LinkProgram(program)
+
+  status: i32
+  gl.GetProgramiv(program, gl.LINK_STATUS, &status)
+  if status == 0 {
+    gl.DeleteProgram(program)
+    return 0
+  }
+
+  return program
+}
+
+gl_init :: proc() {
+  glfw.MakeContextCurrent(window)
+
+  gl.load_up_to(3, 3, glfw.gl_set_proc_address)
+
+  gl.Enable(gl.DEPTH_TEST)
+  gl.DepthFunc(gl.LEQUAL)
+
+  // gl.Enable(gl.BLEND);
+  // gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
+
+  renderer.vt.start_frame = gl_start_frame
+  renderer.vt.end_frame = gl_end_frame
+  renderer.vt.draw = gl_draw
+  renderer.vt.clear = gl_clear
+  renderer.vt.init_texture = gl_init_texture
+  renderer.vt.destroy_texture = gl_destroy_texture
+  renderer.vt.init_screen = gl_init_screen
+
+  enum_conv[Vertex_Mode.None] = gl.TRIANGLES
+  enum_conv[Vertex_Mode.Triangles] = gl.TRIANGLES
+  enum_conv[Vertex_Mode.Triangle_Fan] = gl.TRIANGLE_FAN
+  enum_conv[Vertex_Mode.Triangle_Strip] = gl.TRIANGLE_STRIP
+  enum_conv[Vertex_Mode.Lines] = gl.LINES
+  enum_conv[Vertex_Mode.Line_Strip] = gl.LINE_STRIP
+  enum_conv[Vertex_Mode.Line_Loop] = gl.LINE_LOOP
+  enum_conv[Vertex_Mode.Points] = gl.POINTS
+
+  gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1);
+
+  gl.GenBuffers(1, &vbo)
+  gl.GenBuffers(1, &ebo)
+  gl.GenVertexArrays(1, &vao)
+  _init_vertex_buffer_and_array(vao, vbo, ebo)
+
+  shader_program = _gl_load_shader_program(vert_shader_src, frag_shader_src)
+  projection_loc = gl.GetUniformLocation(shader_program, "projection")
+  view_loc = gl.GetUniformLocation(shader_program, "view")
+  tex0_loc = gl.GetUniformLocation(shader_program, "tex0")
+}
+
+gl_deinit :: proc() {
+  delete(enum_conv)
+
+  destroy_texture(framebuf.color)
+  gl.DeleteRenderbuffers(1, &framebuf.depth)
+  gl.DeleteFramebuffers(1, &framebuf.handle)
+
+  gl.DeleteProgram(shader_program)
+
+  gl.DeleteBuffers(1, &vbo)
+  gl.DeleteVertexArrays(1, &vao)
+}
+
+gl_start_frame :: proc() {
+  gl.BindFramebuffer(gl.FRAMEBUFFER, framebuf.handle)
+  gl.Viewport(0, 0, framebuf.color.size.x, framebuf.color.size.y)
+  renderer.projection = linalg.matrix_ortho3d(
+    f32(0), f32(framebuf.color.size.x),
+    f32(framebuf.color.size.y), 0,
+    -1, 1,
+  )
+}
+
+gl_end_frame :: proc() {
+  gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
+
+  w_width, w_height := glfw.GetWindowSize(window)
+
+  gl.Viewport(0, 0, w_width, w_height)
+
+  renderer.projection = linalg.matrix_ortho3d(
+    f32(0), f32(w_width),
+    0, f32(w_height),
+    -1, 1,
+  )
+
+  draw_rect({0, 0}, {f32(w_width), f32(w_height)}, tex = framebuf.color)
+  flush_batch(&renderer.draw_call)
+}
+
+gl_draw :: proc(draw_call: Draw_Call) {
+  draw_call := draw_call
+
+  gl.UseProgram(shader_program)
+
+  gl.ActiveTexture(gl.TEXTURE0)
+  gl.BindTexture(gl.TEXTURE_2D, draw_call.tex)
+
+  gl.Uniform1i(tex0_loc, 0)
+  gl.UniformMatrix4fv(
+    projection_loc,
+    1,
+    false,
+    transmute([^]f32)(&draw_call.projection),
+  )
+  gl.UniformMatrix4fv(view_loc, 1, false, transmute([^]f32)(&draw_call.view))
+
+  gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
+  gl.BufferData(
+    gl.ARRAY_BUFFER,
+    size_of(Vertex) * len(draw_call.vertices),
+    raw_data(draw_call.vertices),
+    gl.DYNAMIC_DRAW,
+  )
+
+  gl.BindVertexArray(vao)
+
+  if !draw_call.indexed {
+    gl.DrawArrays(
+      enum_conv[draw_call.vertex_mode],
+      0,
+      i32(len(draw_call.vertices)),
+    )
+  } else {
+    gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo)
+    gl.BufferData(
+      gl.ELEMENT_ARRAY_BUFFER,
+      size_of(Index) * len(draw_call.indices),
+      raw_data(draw_call.indices),
+      gl.DYNAMIC_DRAW,
+    )
+
+    gl.DrawElements(
+      enum_conv[draw_call.vertex_mode],
+      i32(len(draw_call.indices)),
+      gl.UNSIGNED_SHORT,
+      nil,
+    )
+    gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0)
+  }
+
+  gl.BindBuffer(gl.ARRAY_BUFFER, 0)
+  gl.BindVertexArray(0)
+}
+
+gl_clear :: proc(col: Color) {
+  gl.ClearColor(col.r, col.g, col.b, col.a)
+  gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+}
+
+gl_init_texture :: proc(
+  texture: ^Texture,
+  data: []u8,
+  channels: i32,
+) {
+  tex: u32
+  gl.GenTextures(1, &tex)
+
+  format := gl.RGBA
+  switch channels {
+  case 3: format = gl.RGB
+  case 4: format = gl.RGBA
+  case: panic("Unsupported amount of channels. Must be either 3 or 4.")
+  }
+
+  gl.BindTexture(gl.TEXTURE_2D, tex)
+  gl.TexImage2D(
+    gl.TEXTURE_2D,
+    0,
+    i32(format),
+    texture.size.x,
+    texture.size.y,
+    0,
+    u32(format),
+    gl.UNSIGNED_BYTE,
+    raw_data(data),
+  )
+
+  gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
+  gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
+
+  gl.GenerateMipmap(gl.TEXTURE_2D)
+
+  texture.handle = tex
+}
+
+gl_destroy_texture :: proc(texture: Texture_Handle) {
+  texture := texture
+  gl.DeleteTextures(1, &texture)
+}
+
+gl_init_screen :: proc(screen_size: Vec2i) {
+  assert(screen_size.x * screen_size.y > 0)
+
+  gl.GenFramebuffers(1, &framebuf.handle)
+  gl.BindFramebuffer(gl.FRAMEBUFFER, framebuf.handle)
+
+  color_tex: u32
+  gl.GenTextures(1, &color_tex)
+  gl.BindTexture(gl.TEXTURE_2D, color_tex)
+  
+  gl.TexImage2D(
+    gl.TEXTURE_2D,
+    0,
+    gl.RGB,
+    screen_size.x,
+    screen_size.y,
+    0,
+    gl.RGB,
+    gl.UNSIGNED_BYTE,
+    nil,
+  )
+  gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
+  gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
+
+  gl.FramebufferTexture2D(
+    gl.FRAMEBUFFER,
+    gl.COLOR_ATTACHMENT0,
+    gl.TEXTURE_2D,
+    color_tex,
+    0,
+  )
+
+  framebuf.color = Texture {
+    handle = color_tex,
+    size = screen_size,
+  }
+
+  gl.GenRenderbuffers(1, &framebuf.depth)
+  gl.BindRenderbuffer(gl.RENDERBUFFER, framebuf.depth)
+  gl.RenderbufferStorage(
+    gl.RENDERBUFFER,
+    gl.DEPTH_COMPONENT32F,
+    screen_size.x,
+    screen_size.y,
+  );
+  gl.FramebufferRenderbuffer(
+    gl.FRAMEBUFFER,
+    gl.DEPTH_ATTACHMENT,
+    gl.RENDERBUFFER,
+    framebuf.depth,
+  );
+
+  if gl.CheckFramebufferStatus(gl.FRAMEBUFFER) != gl.FRAMEBUFFER_COMPLETE {
+    log.fatal("[OPENGL] Framebuffer could not be completed")
+    os.exit(1)
+  }
+
+  gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
+}