Class: RBGL::Engine::Rasterizer::LineRenderer

Inherits:
Object
  • Object
show all
Defined in:
lib/rbgl/engine/rasterizer/line_renderer.rb

Instance Method Summary collapse

Constructor Details

#initialize(framebuffer, interpolator:, viewport_transform:) ⇒ LineRenderer

Returns a new instance of LineRenderer.



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# File 'lib/rbgl/engine/rasterizer/line_renderer.rb', line 7

def initialize(framebuffer, interpolator:, viewport_transform:)
  @framebuffer = framebuffer
  @interpolator = interpolator
  @viewport_transform = viewport_transform
end

Instance Method Details

#rasterize(v0, v1, fragment_shader, uniforms, state) ⇒ Object 



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# File 'lib/rbgl/engine/rasterizer/line_renderer.rb', line 13

def rasterize(v0, v1, fragment_shader, uniforms, state)
  p0 = @viewport_transform.call(v0[:position])
  p1 = @viewport_transform.call(v1[:position])

  x0 = p0.x.round
  y0 = p0.y.round
  x1 = p1.x.round
  y1 = p1.y.round

  dx = (x1 - x0).abs
  dy = -(y1 - y0).abs
  sx = x0 < x1 ? 1 : -1
  sy = y0 < y1 ? 1 : -1
  err = dx + dy
  total_dist = Math.sqrt((x1 - x0)**2 + (y1 - y0)**2)

  loop do
    t = interpolation_factor(x0, y0, p0, total_dist)
    corrected_weights = @interpolator.perspective_correct_weights(
      [v0[:position], v1[:position]],
      [1.0 - t, t]
    )
    depth = @interpolator.interpolate_depth([p0.z, p1.z], corrected_weights)
    attributes = @interpolator.interpolate([v0, v1], corrected_weights)

    shade_fragment(x0, y0, depth, attributes, fragment_shader, uniforms, state)
    break if x0 == x1 && y0 == y1

    e2 = 2 * err
    if e2 >= dy
      err += dy
      x0 += sx
    end
    if e2 <= dx
      err += dx
      y0 += sy
    end
  end
end