Module: Gsplat::Backend::RubyAccumulateBackward

Defined in:
lib/gsplat/backend/ruby/accumulate_backward.rb

Overview

Brute-force compositor VJP routed through the one-tile reverse kernel.

Class Method Summary collapse

Class Method Details

.backward(means2d, conics, opacities, colors, backgrounds, width, height, render_alphas, last_ids, grad_render_colors, grad_render_alphas) ⇒ Object

rubocop:disable Metrics/ParameterLists



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# File 'lib/gsplat/backend/ruby/accumulate_backward.rb', line 10

def backward(means2d, conics, opacities, colors, backgrounds, width, height,
             render_alphas, last_ids, grad_render_colors, grad_render_alphas)
  # rubocop:enable Metrics/ParameterLists
  camera_count, gaussian_count = means2d.shape[0...2]
  offsets = Numo::Int32.zeros(camera_count, 1, 1)
  camera_count.times { |camera_index| offsets[camera_index, 0, 0] = camera_index * gaussian_count }
  flatten_ids = Numo::Int32.new(camera_count * gaussian_count).seq
  gradients, = RubyRasterizeToPixelsBackward.backward(
    means2d,
    conics,
    colors,
    opacities,
    backgrounds,
    nil,
    width,
    height,
    [width, height].max,
    offsets,
    flatten_ids,
    render_alphas,
    last_ids,
    grad_render_colors,
    grad_render_alphas,
    absgrad: false
  )
  grad_means, grad_conics, grad_colors, grad_opacities, grad_backgrounds = gradients
  [grad_means, grad_conics, grad_opacities, grad_colors, grad_backgrounds]
end