#! ruby
# -*- mode: ruby; coding: utf-8 -*-
# Last updated: <2019/04/15 18:13:04 +0900>
#
# RenderTarget に画像を描画してからshaderに渡す事例
# DXRuby のバージョンによっては、
# RenderTarget#update を呼ぶと描画されなくなる場合もある。

require 'dxruby'

hlsl = <<EOS
  texture tex0;

  sampler Samp0 = sampler_state {
    Texture =<tex0>;
  };

  float4 PS(float2 input : TEXCOORD0) : COLOR0 {
    float4 output;
    // input.y = input.y / 2.0;
    output = tex2D( Samp0, input );
    return output;
  }

  technique HelloShader {
    pass P0 {
      PixelShader = compile ps_2_0 PS();
    }
  }
EOS

core = Shader::Core.new(hlsl)
shader = Shader.new(core, "HelloShader")

img = Image.new(128, 128)
v = 0
img.height.times do |y|
  img.width.times do |x|
    img[x, y] = [255, 0, (v>>8) & 0x0ff, v & 0x0ff]
    v += 2
    v = 0 if v > 0x0ffff
  end
end
imgs = [img]

rt = RenderTarget.new(640, 480)

Window.loop do
  break if Input.keyPush?(K_ESCAPE)

  rt.draw_tile(0, 0, [[0]], imgs, 0, 0, 3, 2)
  rt.update

  x, y = 0, 0
  Window.draw_shader(x, y, rt, shader)
end