From 35d6061198b7915ca8239c6f561f19d21b85ae63 Mon Sep 17 00:00:00 2001
From: Cyberarm <matthewlikesrobots@gmail.com>
Date: Sun, 22 Mar 2020 14:56:22 -0500
Subject: [PATCH] Setup GBuffer for future deferred rendering

---
 i-mic-fps.rb                    |  1 +
 lib/renderer/g_buffer.rb        | 83 +++++++++++++++++++++++++++++++++
 lib/renderer/opengl_renderer.rb |  8 ++--
 3 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 lib/renderer/g_buffer.rb

diff --git a/i-mic-fps.rb b/i-mic-fps.rb
index 4532397..9d7a13f 100644
--- a/i-mic-fps.rb
+++ b/i-mic-fps.rb
@@ -40,6 +40,7 @@ require_relative "lib/managers/collision_manager"
 require_relative "lib/managers/physics_manager"
 
 require_relative "lib/renderer/renderer"
+require_relative "lib/renderer/g_buffer"
 require_relative "lib/renderer/opengl_renderer"
 require_relative "lib/renderer/bounding_box_renderer"
 
diff --git a/lib/renderer/g_buffer.rb b/lib/renderer/g_buffer.rb
new file mode 100644
index 0000000..75047ed
--- /dev/null
+++ b/lib/renderer/g_buffer.rb
@@ -0,0 +1,83 @@
+class IMICFPS
+  class GBuffer
+    include CommonMethods
+
+    def initialize
+      @framebuffer = nil
+      @buffers = [:position, :diffuse, :normal, :texcoord]
+      @textures = {}
+      @ready = false
+
+      create_framebuffer
+    end
+
+    def create_framebuffer
+      buffer = ' ' * 8
+      glGenFramebuffers(1, buffer)
+      @framebuffer = buffer.unpack('L2').first
+
+      glBindFramebuffer(GL_DRAW_FRAMEBUFFER, @framebuffer)
+
+      create_textures
+
+      status = glCheckFramebufferStatus(GL_FRAMEBUFFER)
+
+      if status != GL_FRAMEBUFFER_COMPLETE
+        message = ""
+
+        case status
+        when GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT
+          message = "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT"
+        when GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT
+          message = "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"
+        when GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER
+          message = "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER"
+        when GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER
+          message = "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER"
+        when GL_FRAMEBUFFER_UNSUPPORTED
+          message = "GL_FRAMEBUFFER_UNSUPPORTED"
+        else
+          message = "Unknown error!"
+        end
+        puts "Incomplete framebuffer: #{status}\nError: #{message}"
+      else
+        @ready = true
+      end
+
+      glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0)
+    end
+
+    def create_textures
+      @buffers.size.times do |i|
+        buffer = ' ' * 8
+        glGenTextures(1, buffer)
+        texture_id = buffer.unpack('L2').first
+        @textures[@buffers[i]] = texture_id
+
+        glBindTexture(GL_TEXTURE_2D, texture_id)
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, window.width, window.height, 0, GL_RGB, GL_FLOAT, nil)
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i, GL_TEXTURE_2D, texture_id, 0)
+      end
+
+      buffer = ' ' * 8
+      glGenTextures(1, buffer)
+      texture_id = buffer.unpack('L2').first
+      @textures[:depth] = texture_id
+
+      glBindTexture(GL_TEXTURE_2D, texture_id)
+      glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32F, window.width, window.height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, nil)
+      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, texture_id, 0)
+
+      draw_buffers = [ GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3 ]
+      glDrawBuffers(draw_buffers.size, draw_buffers.pack("I*"))
+    end
+
+    def clean_up
+      glDeleteFramebuffers(@framebuffer)
+
+      @textures.values.each do |id|
+        glDeleteTextures(id)
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/renderer/opengl_renderer.rb b/lib/renderer/opengl_renderer.rb
index c3f63da..138b5f6 100644
--- a/lib/renderer/opengl_renderer.rb
+++ b/lib/renderer/opengl_renderer.rb
@@ -2,8 +2,10 @@ class IMICFPS
   class OpenGLRenderer
     include CommonMethods
 
+    @@immediate_mode_warning = false
+
     def initialize
-      @immediate_mode_warning = false
+      @g_buffer = GBuffer.new
     end
 
     def draw_object(camera, lights, object)
@@ -32,8 +34,8 @@ class IMICFPS
           object.draw
         end
       else
-        puts "Shader 'default' failed to compile, using immediate mode for rendering..." unless @immediate_mode_warning
-        @immediate_mode_warning = true
+        puts "Shader 'default' failed to compile, using immediate mode for rendering..." unless @@immediate_mode_warning
+        @@immediate_mode_warning = true
 
         gl_error?
         lights.each(&:draw)