Moved files around, renamed Matrix to Transform

lib/cyberarm_engine/transform.rb

@@ -0,0 +1,89 @@
+module CyberarmEngine
+  class Transform
+    attr_reader :elements
+    def initialize(matrix)
+      @elements = matrix
+
+      raise "Transform is wrong size! Got #{@elements.size}, expected 16" if 16 != @elements.size
+    end
+
+    def error(pos)
+      p @elements
+      Vector.new(@elements[3], @elements[7]) - pos
+    end
+
+    def self.rotate(angle, rotate_around = nil)
+      double c = Math.cos(angle).degrees_to_radians
+      double s = Math.sin(angle).degrees_to_radians
+      matrix = [
+          +c, +s, 0, 0,
+          -s, +c, 0, 0,
+          0,  0,  1, 0,
+          0,  0,  0, 1,
+      ]
+
+      rotate_matrix = Transform.new(matrix, rows: 4, columns: 4)
+
+      if rotate_around && (rotate_around.x != 0.0 || rotate_around.y != 0.0)
+        negative_rotate_around = Vector.new(-rotate_around.x, -rotate_around.y, -rotate_around.z)
+
+        rotate_matrix = concat(
+          concat(translate(negative_rotate_around), rotate_matrix),
+          translate(rotate_around)
+        )
+      end
+
+      return rotate_matrix
+    end
+
+    def self.translate(vector)
+      x, y, z = vector.to_a[0..2]
+      matrix = [
+        1, 0, 0, 0,
+        0, 1, 0, 0,
+        0, 0, 1, 0,
+        x, y, z, 1,
+      ]
+
+      Transform.new(matrix)
+    end
+
+    def self.scale(vector, center_around = nil)
+      scale_x, scale_y, scale_z = vector.to_a[0..2]
+      matrix = [
+        scale_x, 0,       0,       0,
+        0,       scale_y, 0,       0,
+        0,       0,       scale_z, 0,
+        0,       0,       0,       1,
+      ]
+
+      scale_matrix = Transform.new(matrix)
+
+      if center_around && (center_around.x != 0.0 || center_around.y != 0.0)
+        negative_center_around = Vector.new(-center_around.x, -center_around.y, -center_around.z)
+
+        scale_matrix = concat(
+          concat(translate(negative_center_around), scale_matrix),
+          translate(center_around)
+        )
+      end
+
+      return scale_matrix
+    end
+
+    def self.concat(left, right)
+      matrix = Array.new(left.elements.size)
+      rows = 4
+
+      matrix.size.times do |i|
+        matrix[i] = 0
+
+        rows.times do |j|
+          matrix[i] += left.elements[i / rows * rows + j] * right.elements[i % rows + j * rows]
+        end
+      end
+
+      Transform.new(matrix)
+    end
+  end
+end