Simplifying things with a common utils module

lib/opengl/gl_utils.rb

@@ -0,0 +1,88 @@
+java_import org.lwjgl.opengl.GL20
+java_import org.lwjgl.opengl.GL11
+
+module OpenGL::GLUtils
+
+		# initialised the program with the shaders that have been passed through
+		# @param [String] vertex_shader
+		# @param [String] frag_shader
+		def compile_program(vertex_shader, frag_shader)
+			vertex_shader = compile_shader(GL20::GL_VERTEX_SHADER, vertex_shader)
+			frag_shader = compile_shader(GL20::GL_FRAGMENT_SHADER, frag_shader)
+
+			program_id = GL20.gl_create_program
+
+			GL20.gl_attach_shader(program_id, vertex_shader)
+			GL20.gl_attach_shader(program_id, frag_shader)
+			GL20.gl_link_program(program_id)
+			GL20.gl_validate_program(program_id)
+
+			puts "Validate Program", GL20.gl_get_program_info_log(program_id, 200)
+
+			GL20.gl_delete_shader(vertex_shader)
+			GL20.gl_delete_shader(frag_shader)
+
+			program_id
+		end
+
+		# create a shader for you, and return the id
+		# @param [Integer] shader_type the GL20 shader type int
+		# @param [String] file_name the name of the glsl file
+		# @return [Integer] the shader id
+		def compile_shader(shader_type, file_name)
+			shader_id = GL20.gl_create_shader(shader_type)
+			shader_file = File.new File.expand_path("../../glsl/#{file_name}", __FILE__)
+
+			GL20.gl_shader_source(shader_id, shader_file.read)
+			GL20.gl_compile_shader(shader_id)
+
+			puts file_name, GL20.gl_get_shader_info_log(shader_id, 200)
+
+			raise "Error compiling shader #{file_name}" if (GL20.gl_get_shader(shader_id, GL20::GL_COMPILE_STATUS) == GL11::GL_FALSE)
+
+			shader_id
+		end
+
+		# run the render loop
+		# @param [Proc] display
+		def render_loop(&display_block)
+
+			while(!Display.is_close_requested)
+				display_block.call
+
+				# we'll force it down to 60 FPS
+				Display.sync(60)
+				Display.update()
+			end
+
+		end
+
+		def destory_display
+			Display.destroy
+		end
+
+		def create_display(title, width=800, height=600)
+			Display.display_mode = DisplayMode.new(width, height)
+			Display.title = title
+			Display.create
+		end
+
+		# hook for class methods
+		def self.included(base)
+			base.extend(ClassMethods)
+		end
+
+		module ClassMethods
+
+			# creates a start script for this item
+			def add_start
+				class << self
+					define_method :start do
+						self.new
+					end
+				end
+			end
+
+		end
+
+end

lib/opengl/show_triangle_colours.rb

@@ -6,9 +6,13 @@
 java_import org.lwjgl.opengl.GL30
 java_import org.lwjgl.BufferUtils
 
+require "opengl/gl_utils"
+
 #
 # Let's display a triangle, with a gradient
 class OpenGL::ShowTriangleColours
+	include OpenGL::GLUtils
+	add_start
 
 	# initialise
 	def initialize
@@ -25,26 +29,17 @@ def initialize
 		#pre calculate the byte size of a float.
 		@float_size = (java.lang.Float::SIZE/8)
 
-		Display.display_mode = DisplayMode.new(800, 600)
-		Display.title = "I am a triangle! (with different colours!)"
-		Display.create
+		create_display("I am a triangle! (with different colours!)")
 
 		#initialise the viewport
 		GL11.gl_viewport(0, 0, Display.width, Display.height)
 
-		init_program
+		@program_id = compile_program 'colour_gradient_vertex.glsl', 'colour_grandient_fragment.glsl'
 		init_vertex_buffers
 
-		while(!Display.is_close_requested)
-
-			display
+		render_loop { display }
 
-			# we'll force it down to 60 FPS
-			Display.sync(60)
-			Display.update()
-		end
-
-		Display.destroy
+		close_display
 
 
 	end
@@ -78,24 +73,6 @@ def display
 
 	end
 
-	# initialise the program
-	def init_program
-		vertex_shader = create_shader(GL20::GL_VERTEX_SHADER, 'colour_gradient_vertex.glsl')
-		frag_shader = create_shader(GL20::GL_FRAGMENT_SHADER, 'colour_grandient_fragment.glsl')
-
-		@program_id = GL20.gl_create_program
-		GL20.gl_attach_shader(@program_id, vertex_shader)
-		GL20.gl_attach_shader(@program_id, frag_shader)
-		GL20.gl_link_program(@program_id)
-		GL20.gl_validate_program(@program_id)
-
-		puts "Validate Program", GL20.gl_get_program_info_log(@program_id, 200)
-
-		GL20.gl_delete_shader(vertex_shader)
-		GL20.gl_delete_shader(frag_shader)
-
-	end
-
 	# initialise the vertex buffers
 	def init_vertex_buffers
 		#vao_id = GL30.gl_gen_vertex_arrays
@@ -117,25 +94,4 @@ def init_vertex_buffers
 		#GL30.gl_bind_vertex_array(0)
 	end
 
-	# create a shader for you, and return the id
-	# @param [Integer] shader_type the GL20 shader type int
-	# @param [String] file_name the name of the glsl file
-	# @return [Integer] the shader id
-	def create_shader(shader_type, file_name)
-		shader_id = GL20.gl_create_shader(shader_type)
-		shader_file = File.new File.expand_path("../../glsl/#{file_name}", __FILE__)
-
-		GL20.gl_shader_source(shader_id, shader_file.read)
-		GL20.gl_compile_shader(shader_id)
-
-		puts file_name, GL20.gl_get_shader_info_log(shader_id, 200)
-
-		shader_id
-	end
-
-	# off we go
-	def self.start
-		OpenGL::ShowTriangleColours.new
-	end
-
 end