From c6beab3e99191f2b68da87a1f56407e4670ec891 Mon Sep 17 00:00:00 2001
From: Cyberarm <matthewlikesrobots@gmail.com>
Date: Sun, 6 Oct 2019 21:35:10 -0500
Subject: [PATCH] Added Matrix, incomplete.

---
 lib/cyberarm_engine.rb            |   1 +
 lib/cyberarm_engine/lib/matrix.rb | 115 ++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+)
 create mode 100644 lib/cyberarm_engine/lib/matrix.rb

diff --git a/lib/cyberarm_engine.rb b/lib/cyberarm_engine.rb
index 190d94f..62e349d 100644
--- a/lib/cyberarm_engine.rb
+++ b/lib/cyberarm_engine.rb
@@ -15,6 +15,7 @@ require_relative "cyberarm_engine/engine"
 
 require_relative "cyberarm_engine/lib/bounding_box"
 require_relative "cyberarm_engine/lib/vector"
+require_relative "cyberarm_engine/lib/matrix"
 require_relative "cyberarm_engine/lib/ray"
 require_relative "cyberarm_engine/lib/shader" if defined?(OpenGL)
 require_relative "cyberarm_engine/background"
diff --git a/lib/cyberarm_engine/lib/matrix.rb b/lib/cyberarm_engine/lib/matrix.rb
new file mode 100644
index 0000000..7dc3d2d
--- /dev/null
+++ b/lib/cyberarm_engine/lib/matrix.rb
@@ -0,0 +1,115 @@
+module CyberarmEngine
+  class Matrix
+    attr_reader :elements, :rows, :columns
+    def initialize(matrix, rows:, columns:)
+      @elements = matrix
+      @rows = rows
+      @columns = columns
+
+      raise "Matrix is wrong size! Got #{@elements.size}, expected #{@rows * @columns}" if @rows * @columns != @elements.size
+    end
+
+    def +(other)
+    end
+
+    def -(other)
+    end
+
+    def *(other)
+    end
+
+    def cofactor
+    end
+
+    def adjoint
+      sign = 1
+      matrix = @elements.clone
+
+      @rows.times do |row|
+        @columns.times do |columns|
+        end
+      end
+    end
+
+    def determinant
+    end
+
+    # https://www.geeksforgeeks.org/adjoint-inverse-matrix/
+    def inverse
+    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 = Matrix.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,
+      ]
+
+      Matrix.new(matrix, rows: 4, columns: 4)
+    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 = Matrix.new(matrix, rows: 4, columns: 4)
+
+      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 = left.rows
+
+      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
+
+      Matrix.new(matrix, rows: 4, columns: 4)
+    end
+  end
+end
\ No newline at end of file