From 7c1f3508c49706e394b71b3de92513078f67b7be Mon Sep 17 00:00:00 2001
From: Edouard DUPIN <yui.heero@gmail.com>
Date: Sat, 18 Apr 2020 00:42:13 +0200
Subject: [PATCH] [DEV] tutorial 5 implementation

---
 src/engineTester/MainGameLoop.java |  7 ++-
 src/shaders/ShaderProgram.java     | 72 ++++++++++++++++++++++++++++++
 src/shaders/StaticShader.java      | 16 +++++++
 src/shaders/fragmentShader.txt     | 10 +++++
 src/shaders/vertexShader.txt       | 12 +++++
 5 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 src/shaders/ShaderProgram.java
 create mode 100644 src/shaders/StaticShader.java
 create mode 100644 src/shaders/fragmentShader.txt
 create mode 100644 src/shaders/vertexShader.txt

diff --git a/src/engineTester/MainGameLoop.java b/src/engineTester/MainGameLoop.java
index 0b01f5f..ccc34b2 100644
--- a/src/engineTester/MainGameLoop.java
+++ b/src/engineTester/MainGameLoop.java
@@ -6,6 +6,7 @@ import renderEngine.DisplayManagerDraw;
 import renderEngine.Loader;
 import renderEngine.RawModel;
 import renderEngine.Renderer;
+import shaders.StaticShader;
 
 /**
  * This class contains the main method and is used to test the engine.
@@ -27,8 +28,8 @@ public class MainGameLoop {
 		DisplayManager manager = new DisplayManager();
 		Loader loader = new Loader();
 		Renderer renderer = new Renderer();
-		
 		manager.init();
+		StaticShader shader = new StaticShader();
 		
 		float[] vertices = {
 				-0.5f, 0.5f, 0f,//v0
@@ -48,11 +49,13 @@ public class MainGameLoop {
 			@Override
 			public void draw() {
 				renderer.prepare();
+				shader.start();
 				renderer.render(model);
+				shader.stop();
 			}
 		});
 		manager.loop();
-
+		shader.cleanUp();
 		loader.cleanUp();
 		manager.unInit();
 	}
diff --git a/src/shaders/ShaderProgram.java b/src/shaders/ShaderProgram.java
new file mode 100644
index 0000000..b50aeb1
--- /dev/null
+++ b/src/shaders/ShaderProgram.java
@@ -0,0 +1,72 @@
+package shaders;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL20;
+
+public abstract class ShaderProgram {
+
+	private int programID;
+	private int vertexShaderID;
+	private int fragmentShaderID;
+
+	public ShaderProgram (String vertexFile, String fragmentFile) {
+		vertexShaderID = loadShader(vertexFile, GL20.GL_VERTEX_SHADER);
+		fragmentShaderID = loadShader(fragmentFile, GL20.GL_FRAGMENT_SHADER);
+		programID = GL20.glCreateProgram();
+		GL20.glAttachShader(programID, vertexShaderID);
+		GL20.glAttachShader(programID, fragmentShaderID);
+		GL20.glLinkProgram(programID);
+		GL20.glValidateProgram(programID);
+		bindAttributes();
+	}
+
+	public void start() {
+		GL20.glUseProgram(programID);
+	}
+	public void stop() {
+		GL20.glUseProgram(0);
+	}
+	public void cleanUp() {
+		stop();
+		GL20.glDetachShader(programID, vertexShaderID);
+		GL20.glDetachShader(programID, fragmentShaderID);
+		GL20.glDeleteShader(vertexShaderID);
+		GL20.glDeleteShader(fragmentShaderID);
+		GL20.glDeleteProgram(programID);
+	}
+	
+	protected abstract void bindAttributes();
+	
+	protected void bindAttribute(int attribute, String variableName) {
+		GL20.glBindAttribLocation(programID, attribute, variableName);
+	}
+	
+	private static int loadShader(String file, int type) {
+		StringBuilder shaderSource = new StringBuilder();
+		try {
+			BufferedReader reader = new BufferedReader(new FileReader(file));
+			String line;
+			while((line = reader.readLine()) != null) {
+				shaderSource.append(line).append("\n");
+			}
+			reader.close();
+		} catch(IOException e) {
+			System.err.println("Could not read the file!");
+			e.printStackTrace();
+			System.exit(-1);
+		}
+		int shaderID = GL20.glCreateShader(type);
+		GL20.glShaderSource(shaderID, shaderSource);
+		GL20.glCompileShader(shaderID);
+		if (GL20.glGetShaderi(shaderID, GL20.GL_COMPILE_STATUS) == GL11.GL_FALSE) {
+			System.out.println(GL20.glGetShaderInfoLog(shaderID, 500));
+			System.out.println("Could not compile the shader");
+			System.exit(-1);
+		}
+		return shaderID;
+	}
+}
diff --git a/src/shaders/StaticShader.java b/src/shaders/StaticShader.java
new file mode 100644
index 0000000..f6ab20c
--- /dev/null
+++ b/src/shaders/StaticShader.java
@@ -0,0 +1,16 @@
+package shaders;
+
+public class StaticShader extends ShaderProgram {
+	private static final String VERTEX_FILE = "src/shaders/vertexShader.txt";
+	private static final String FRAGMENT_FILE = "src/shaders/fragmentShader.txt";
+	
+	public StaticShader() {
+		super(VERTEX_FILE, FRAGMENT_FILE);
+	}
+
+	@Override
+	protected void bindAttributes() {
+		super.bindAttribute(0, "position");
+	}
+	
+}
diff --git a/src/shaders/fragmentShader.txt b/src/shaders/fragmentShader.txt
new file mode 100644
index 0000000..3920269
--- /dev/null
+++ b/src/shaders/fragmentShader.txt
@@ -0,0 +1,10 @@
+#version 400 core
+
+in vec3 colour;
+
+out vec4 out_Color;
+
+void main(void) {
+	out_Color = vec4(colour, 1.0); 
+}
+
diff --git a/src/shaders/vertexShader.txt b/src/shaders/vertexShader.txt
new file mode 100644
index 0000000..8399bc2
--- /dev/null
+++ b/src/shaders/vertexShader.txt
@@ -0,0 +1,12 @@
+#version 400 core
+
+in vec3 position;
+
+out vec3 colour;
+
+void main(void) {
+
+	gl_Position = vec4(position, 1.0);
+	colour = vec3(position.x+0.5, 1.0, position.y+0.5);
+}
+