# ============================================================================
# programs.ludic — GLSL from files. A shader file carries no #version line; the
# loader prepends "#version 410 core", any per-variant defines, and the shared
# noise.glsl + lighting.glsl chunks for fragment stages, then compiles it.
# ============================================================================

# Where the renderer's own files are. The shaders belong to this package and ship with
# it — in the Ludic checkout they are under packages/, and in an installed toolchain
# under $LUDIC_HOME/packages/ — so a game built outside the Ludic tree does not have to
# copy them in. The scanned CC0 materials are the other half: too large to ship with a
# toolchain and redistributable from their origin, so they are fetched into the project
# (`ludic assets`) and read from there.
# defines prepended to EVERY program (set before any is built): renderer-wide switches

function r3d_set_paths(render3d_st: mut Render3dState, root: string, assets: string) -> void { render3d_st.r3d_root = root;  render3d_st.r3d_assets = assets }

# Build a program from a vertex + fragment file pair (defines apply to both).
# R3D_PROGRAMS_LOG=<file>: append every program built (vertex, fragment, defines) - the list a
# backend that cannot compile shaders at run time (Vulkan: SPIR-V is built ahead) must cover
@alloc_ok("profiling and statistics, only under R3D_PROF / R3D_DRAWSTATS")
function r3d_program_log(render3d_st: mut Render3dState, vs: string, fs: string, defines: string) -> void {
  if render3d_st.r3d_prog_log < 0 { render3d_st.r3d_prog_log = 0;  if r3d_env_has(render3d_st, "R3D_PROGRAMS_LOG") { render3d_st.r3d_prog_log = 1 } }
  if render3d_st.r3d_prog_log == 0 { return }
  let f = file_open(r3d_env(render3d_st, "R3D_PROGRAMS_LOG"), "ab")
  if f == null { return }
  # one line per program: the defines' newlines become ';' so a variant is one line
  let defs = Text.replace(`{render3d_st.r3d_global_defs}{defines}`, "\n", ";")
  let line = `{vs}|{fs}|{defs}\n`
  file_write(f, line, len(line))
  file_close(f)
}
@alloc_ok("made once per resource and kept for its life (a texture, program, sampler, view, layout or memory block is created when first asked for)")
function r3d_program(render3d_st: mut Render3dState, vs: string, fs: string, defines: string) -> int {
  r3d_program_log(render3d_st, vs, fs, defines)
  let defs = `{render3d_st.r3d_global_defs}{defines}`
  let p = gpu_program(render3d_st, vs, fs, defs)
  free(defs)                                  # the program's key is built from it, not kept
  if p == 0 { print(`r3d: program failed: {vs} + {fs}`) }
  return p
}

# Bind a texture to a unit and point a sampler uniform at it.
function r3d_bind_tex(render3d_st: mut Render3dState, prog: int, name: string, unit: int, kind: int, tex: int) -> void { gpu_bind_sampler(render3d_st, prog, name, unit, kind, tex) }
function r3d_bind_2d(render3d_st: mut Render3dState, prog: int, name: string, unit: int, tex: int) -> void { gpu_bind_sampler(render3d_st, prog, name, unit, GPU_TEX2D, tex) }

# A framebuffer with one colour texture (and optionally a depth texture).
property Target {
  @owns(GpuFramebuffer) fbo:   int = 0,
  @owns(GpuTexture) color: int = 0,
  @owns(GpuTexture) depth: int = 0,
  w:     int = 0,
  h:     int = 0
}
@alloc_ok("made once per resource and kept for its life (a texture, program, sampler, view, layout or memory block is created when first asked for)")
@creates(Target)
function target_new(render3d_st: mut Render3dState, w: int, h: int, ifmt: int, fmt: int, ty: int, with_depth: bool, filter: int) -> Target {
  let t = new Target
  t.w = w;  t.h = h
  t.fbo = gpu_fb_new(render3d_st)
  gpu_fb_bind(render3d_st, t.fbo)
  t.color = tex_target(render3d_st, w, h, ifmt, fmt, ty, filter)
  gpu_fb_color(render3d_st, 0, t.color)
  if with_depth {
    t.depth = tex_target(render3d_st, w, h, GL_DEPTH_COMPONENT32F, GL_DEPTH_COMPONENT, GL_FLOAT, GL_NEAREST)
    gpu_fb_depth(render3d_st, t.depth)
  }
  let st = gpu_fb_status(render3d_st)
  if st != GL_FRAMEBUFFER_COMPLETE { print(`r3d: framebuffer incomplete {st} ({w}x{h})`) }
  gpu_fb_bind(render3d_st, 0)
  return t
}
@releases(Target)
function target_free(render3d_st: mut Render3dState, t: Target) -> void {
  if t == null { return }
  gpu_fb_free(render3d_st, t.fbo)
  gpu_tex_free(render3d_st, t.color)
  if t.depth != 0 { gpu_tex_free(render3d_st, t.depth) }
}
function target_bind(render3d_st: mut Render3dState, t: Target) -> void {
  gpu_fb_bind(render3d_st, t.fbo)
  gpu_viewport(render3d_st, 0, 0, t.w, t.h)
}