render_clip.nelua

--[[
Copyright (c) 2021-present André Luiz Alvares
Nene is licensed under the Zlib license.
Please refer to the LICENSE file for details
SPDX-License-Identifier: Zlib
]]

-- This example shows how to using render clipping using a rectangle.

local Nene = require 'nene.core'
local Color = require 'nene.color'
local Rect = require 'nene.math.rect'

local function rects()
  local ok = Nene.init('nene render rect clip', 256, 256)
  assert(ok, 'error: nene initialization failed')

  -- create two rects
  local rect_clip: Rect = { size = { 48, 48 } }

  repeat
    Nene.update()

    -- copy mouse position to rect_clip position
    local nene = Nene.instance()
    rect_clip.pos = Nene.screen_point_to_world_pos(nene.mouse_pos):to_vec2i()

    Nene.render_clear(Color.bg)

    -- draw grid
    for i = -16, 16 do
      Nene.render_draw_line({ 16 * i,   -256 }, { 16 * i,    256 }, Color.black, true)
      Nene.render_draw_line({   -256, 16 * i }, {    256, 16 * i }, Color.black, true)
    end

    -- set render clipping
    Nene.set_render_clip(rect_clip, false)
    Nene.render_draw_rect(rect_clip, true, Color.red, true)

    Nene.render_present()
  until Nene.should_quit()

  Nene.terminate()
end

rects()