class SFML::Transform

A 2D affine transformation. Wraps the 3×3 matrix that SFML uses to combine translation, rotation, scaling, and skew. Useful when you want to:

Apply the same transform across many drawables (push it via RenderStates.new(transform: …) instead of repeating position=/rotation= on every shape).
Build a transform from primitive ops without holding a Drawable.

t = SFML::Transform.identity .translate([400, 300]) .rotate(30) .scale([2, 2])

t.transform_point([10, 0]) #=> Vector2(world coord after t) inv = t.inverse #=> reverse mapping

Methods are chainable and mutate in place, returning self. To work with a fresh copy use t.dup. The CSFML constant for the identity is exposed via Transform.identity.

Public Class Methods

from_matrix (arr)

Source

# File lib/sfml/graphics/transform.rb, line 41
def self.from_matrix(arr)
  raise ArgumentError, "expected 9-element matrix, got #{arr.length}" if arr.length != 9
  t = new
  9.times { |i| t.struct[:matrix][i] = arr[i].to_f }
  t
end

Build from a flat row-major 9-element float array. Lays out as: [a, b, c, d, e, f, g, h, i] # SFML stores the 3x3 conceptually as a 4x4 padded

identity ()

Source

# File lib/sfml/graphics/transform.rb, line 33
def self.identity
  new
end

Alias for Transform.new — reads better at call site.

new ()

Source

# File lib/sfml/graphics/transform.rb, line 25
def initialize
  @struct = C::Graphics::Transform.new
  # Start as identity by copying CSFML's sfTransform_Identity.
  identity_bytes = C::Graphics.sfTransform_Identity.pointer.read_bytes(C::Graphics::Transform.size)
  @struct.pointer.write_bytes(identity_bytes)
end

Build a fresh identity Transform. Compose with translate / rotate / scale.

Public Instance Methods

== (other)

Source

# File lib/sfml/graphics/transform.rb, line 128
def ==(other)
  return false unless other.is_a?(Transform)
  C::Graphics.sfTransform_equal(@struct.pointer, other.struct.pointer)
end

Also aliased as: eql?

_vec2 (value)

Source

# File lib/sfml/graphics/transform.rb, line 154
def _vec2(value)
  value.is_a?(Vector2) ? value : Vector2.new(*value)
end

allocate_new_with (native_struct)

Source

# File lib/sfml/graphics/transform.rb, line 146
def allocate_new_with(native_struct)
  t = self.class.allocate
  new_buf = C::Graphics::Transform.new
  new_buf.pointer.write_bytes(native_struct.pointer.read_bytes(C::Graphics::Transform.size))
  t.instance_variable_set(:@struct, new_buf)
  t
end

Returns the allocate new with.

combine (other)

Source

# File lib/sfml/graphics/transform.rb, line 89
def combine(other)
  raise ArgumentError, "Transform#combine needs another SFML::Transform" unless other.is_a?(Transform)
  C::Graphics.sfTransform_combine(@struct.pointer, other.struct.pointer)
  self
end

Multiply this transform by another. t.combine(t2) is t * t2 in left-to-right order (apply t2’s transformation, then t’s).

eql? (other)

Alias for: ==

hash (= matrix.hash)

Source

# File lib/sfml/graphics/transform.rb, line 134
    def hash = matrix.hash

    # String representation for debugging.
    def to_s = "Transform(#{matrix.map { |v| v.round(3) }.inspect})"
    alias inspect to_s

    # @!visibility private
    attr_reader :struct

    private

    # Returns the allocate new with.
    def allocate_new_with(native_struct)
      t = self.class.allocate
      new_buf = C::Graphics::Transform.new
      new_buf.pointer.write_bytes(native_struct.pointer.read_bytes(C::Graphics::Transform.size))
      t.instance_variable_set(:@struct, new_buf)
      t
    end

    def _vec2(value)
      value.is_a?(Vector2) ? value : Vector2.new(*value)
    end
  end
end

Returns the hash.

initialize_dup (other)

Source

# File lib/sfml/graphics/transform.rb, line 50
def initialize_dup(other)
  super
  @struct = C::Graphics::Transform.new
  @struct.pointer.write_bytes(other.struct.pointer.read_bytes(C::Graphics::Transform.size))
end

Deep-copy hook — t.dup clones the underlying matrix, not just the pointer.

Calls superclass method

inverse ()

Source

# File lib/sfml/graphics/transform.rb, line 97
def inverse
  result = C::Graphics.sfTransform_getInverse(@struct.pointer)
  t = allocate_new_with(result)
  t
end

Return a new Transform that’s the inverse of this one — applying both in sequence yields the identity.

matrix ()

Source

# File lib/sfml/graphics/transform.rb, line 124
def matrix
  (0...9).map { |i| @struct[:matrix][i] }
end

Read the matrix as a flat 9-element Array of floats (row-major).

rotate (degrees, center: nil)

Source

# File lib/sfml/graphics/transform.rb, line 65
def rotate(degrees, center: nil)
  if center
    c = _vec2(center)
    C::Graphics.sfTransform_rotateWithCenter(@struct.pointer, degrees.to_f, c.to_native_f)
  else
    C::Graphics.sfTransform_rotate(@struct.pointer, degrees.to_f)
  end
  self
end

Apply a rotation by degrees. Optional center to pivot around a non-origin point.

scale (factors, center: nil)

Source

# File lib/sfml/graphics/transform.rb, line 76
def scale(factors, center: nil)
  f = _vec2(factors)
  if center
    c = _vec2(center)
    C::Graphics.sfTransform_scaleWithCenter(@struct.pointer, f.to_native_f, c.to_native_f)
  else
    C::Graphics.sfTransform_scale(@struct.pointer, f.to_native_f)
  end
  self
end

Apply a scale. With center:, scales around that pivot.

to_s (= "Transform(

Source

# File lib/sfml/graphics/transform.rb, line 137
  def to_s = "Transform(#{matrix.map { |v| v.round(3) }.inspect})"
  alias inspect to_s

  # @!visibility private
  attr_reader :struct

  private

  # Returns the allocate new with.
  def allocate_new_with(native_struct)
    t = self.class.allocate
    new_buf = C::Graphics::Transform.new
    new_buf.pointer.write_bytes(native_struct.pointer.read_bytes(C::Graphics::Transform.size))
    t.instance_variable_set(:@struct, new_buf)
    t
  end

  def _vec2(value)
    value.is_a?(Vector2) ? value : Vector2.new(*value)
  end
end

String representation for debugging.

transform_point (point)

Source

# File lib/sfml/graphics/transform.rb, line 104
def transform_point(point)
  vec = _vec2(point)
  r   = C::Graphics.sfTransform_transformPoint(@struct.pointer, vec.to_native_f)
  Vector2.new(r[:x], r[:y])
end

Map a point through the transform. Returns a Vector2.

transform_rect (rect)

Source

# File lib/sfml/graphics/transform.rb, line 111
def transform_rect(rect)
  raise ArgumentError, "Transform#transform_rect needs a SFML::Rect" unless rect.is_a?(Rect)
  native = C::Graphics::FloatRect.new
  native[:position][:x] = rect.x.to_f
  native[:position][:y] = rect.y.to_f
  native[:size][:x]     = rect.width.to_f
  native[:size][:y]     = rect.height.to_f

  r = C::Graphics.sfTransform_transformRect(@struct.pointer, native)
  Rect.from_native(r)
end

Map a SFML::Rect through the transform. Returns a new Rect.

translate (offset)

Source

# File lib/sfml/graphics/transform.rb, line 57
def translate(offset)
  vec = _vec2(offset)
  C::Graphics.sfTransform_translate(@struct.pointer, vec.to_native_f)
  self
end

Apply a translation. Mutates self.