Added shader support, removed unused debugging puts statements and fixed Gosu Font.draw deprecation warning.

lib/renderer/shader.rb

@@ -0,0 +1,112 @@
+class IMICFPS
+  # Ref: https://github.com/vaiorabbit/ruby-opengl/blob/master/sample/OrangeBook/brick.rb
+  class Shader
+    include OpenGL
+
+    def initialize(name:, vertex_file:, fragment_file:)
+      @name = name
+      @vertex_file   = vertex_file
+      @fragment_file = fragment_file
+      @compiled = false
+
+      @error_buffer_size = 1024
+
+      create_shaders
+      compile_shaders
+
+      if @compiled
+        ShaderManager.add_shader(@name, self)
+      else
+        puts "FAILED to compile shader: #{@name}", ""
+      end
+    end
+
+    def shader_files_exist?
+      File.exists?(@vertex_file) && File.exists?(@fragment_file)
+    end
+
+    def create_shaders
+      return unless shader_files_exist?
+
+      @vertex   = glCreateShader(GL_VERTEX_SHADER)
+      @fragment = glCreateShader(GL_FRAGMENT_SHADER)
+
+      source = [File.read(@vertex_file)].pack('p')
+      size   = [File.size(@vertex_file)].pack('I')
+      glShaderSource(@vertex, 1, source, size)
+
+      source = [File.read(@fragment_file)].pack('p')
+      size   = [File.size(@fragment_file)].pack('I')
+      glShaderSource(@fragment, 1, source, size)
+    end
+
+    def compile_shaders
+      return unless shader_files_exist?
+
+      glCompileShader(@vertex)
+      buffer = '    '
+      glGetShaderiv(@vertex, GL_COMPILE_STATUS, buffer)
+      compiled = buffer.unpack('L')[0]
+
+      if compiled == 0
+        log = ' ' * @error_buffer_size
+        glGetShaderInfoLog(@vertex, @error_buffer_size, nil, log)
+        puts "Vertex Shader InfoLog:\n#{log.strip}\n"
+        puts "Shader Compiled status: #{compiled}"
+        puts
+      end
+
+      glCompileShader(@fragment)
+      buffer = '    '
+      glGetShaderiv(@fragment, GL_COMPILE_STATUS, buffer)
+      compiled = buffer.unpack('L')[0]
+
+      if compiled == 0
+        log = ' ' * @error_buffer_size
+        glGetShaderInfoLog(@fragment, @error_buffer_size, nil, log)
+        puts "Fragment Shader InfoLog:\n#{log.strip}\n"
+        puts "Shader Compiled status: #{compiled}"
+        puts
+      end
+
+      @program = glCreateProgram
+      glAttachShader(@program, @vertex)
+      glAttachShader(@program, @fragment)
+      glLinkProgram(@program)
+
+      buffer = '    '
+      glGetProgramiv(@program, GL_LINK_STATUS, buffer)
+      linked = buffer.unpack('L')[0]
+
+      if linked == 0
+        log = ' ' * @error_buffer_size
+        glGetProgramInfoLog(@program, @error_buffer_size, nil, log)
+        puts "Program InfoLog:\n#{log.strip}\n"
+      end
+
+      @compiled = linked == 0 ? false : true
+    end
+
+    # Returns the location of a uniform variable
+    def variable(variable)
+      loc = glGetUniformLocation(@program, variable)
+      if (loc == -1)
+        puts "Shader:\"#{@name}\" No such uniform named #{variable}"
+      end
+      return loc
+    end
+
+    def use(&block)
+      return unless compiled?
+      glUseProgram(@program)
+
+      block.call(self) if block
+
+      glUseProgram(0)
+    end
+
+    def compiled?
+      @compiled
+    end
+  end
+end