Crude OpenGL triangle example

CMakeLists.txt

@@ -67,9 +67,11 @@ SET(CMAKE_CXX_FLAGS
 SET(SOURCE_FILES
     src/game/game.cpp
 
+    src/graphics/opengl/opengl.cpp
+
     src/input/input.cpp
 
-    src/scene/scene.cpp
+    src/scene/example/example.cpp
 
     src/window/window.cpp
 
@@ -112,6 +114,8 @@ ENDIF()
 
 TARGET_LINK_LIBRARIES(HomdEngine
     sdl2
+    glew32
+    opengl32
     ${win32_link}
 )
 

README.md

@@ -0,0 +1,18 @@
+# Setting Up Environment for Windows
+
+- Install MSYS2 from [here](https://www.msys2.org/) to `C:\msys64`
+- Once installed, open MSYS2 CLANG64 and run the following command:
+
+```
+pacman -S mingw-w64-clang-x86_64-toolchain mingw-w64-clang-x86_64-cmake mingw-w64-clang-x86_64-SDL2 mingw-w64-clang-x86_64-glew
+```
+
+- Add `C:\msys64\clang64\bin` to your `Path` from Environment Variables.
+- Run the following steps:
+
+```
+mkdir build
+cd build
+cmake ..
+ninja
+```

src/game/game.cpp

@@ -4,12 +4,14 @@
  */
 
 #include <game/game.h>
-#include <scene/scene.h>
+#include <scene/example/example.h>
+#include <graphics/opengl/opengl.h>
 
 Game::Game() {
     this->pWindow = new Window(this);
+    this->pRenderer = new OpenGL(this);
     this->pInput = new Input(this);
-    this->scenes.push(new Scene);
+    this->scenes.push(new Example(this));
 }
 
 void Game::loop() {
@@ -22,5 +24,7 @@ void Game::loop() {
             this->scenes.pop();
             continue;
         }
+
+        this->scenes.top()->draw();
     }
 }

src/game/game.h

@@ -11,6 +11,7 @@
 #include <stack>
 
 class Scene;
+class Graphics;
 
 class Game {
     bool done = false;
@@ -19,6 +20,7 @@ class Game {
    public:
     Window* pWindow;
     Input* pInput;
+    Graphics* pRenderer;
 
     Game();
     ~Game() = default;

src/graphics/graphics.h

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
+ * All rights reserved
+ */
+
+#ifndef _HOMD_GRAPHICS
+#define _HOMD_GRAPHICS
+
+class Game;
+
+class Graphics {
+   public:
+    Game* game;
+    Graphics() = default;
+    virtual ~Graphics() = default;
+    virtual void drawSomething() = 0;
+};
+
+#endif

src/graphics/opengl/opengl.cpp

@@ -0,0 +1,82 @@
+/**
+ * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
+ * All rights reserved
+ */
+
+#include <GLES3/gl3.h>
+#define GLEW_STATIC
+#include <SDL2/SDL_video.h>
+#include <GL/glew.h>
+
+#include <graphics/opengl/opengl.h>
+#include <game/game.h>
+#include <window/window.h>
+#include <string>
+#include <iostream>
+
+static const GLchar* vertexShaderSrc = R"(
+    attribute vec4 position;
+    void main() {
+        gl_Position = vec4(position.xyz, 1.0);
+    }
+)";
+
+static const GLchar* fragmentShaderSrc = R"(
+    precision mediump float;
+    void main() {
+        gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
+    }
+)";
+
+static GLfloat vertices[] = {0.0, 0.8, -0.8, -0.8, 0.8, -0.8};
+
+OpenGL::OpenGL(Game* pGame) {
+    glewExperimental = GL_TRUE;
+    this->game = pGame;
+
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+    SDL_GL_SetSwapInterval(0);
+    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+
+    this->context = SDL_GL_CreateContext(this->game->pWindow->window);
+
+    GLenum err = glewInit();
+    std::cout << glewGetErrorString(err);
+
+    GLuint vertexArrObj;
+    glGenVertexArrays(1, &vertexArrObj);
+    glBindVertexArray(vertexArrObj);
+
+    GLuint vertexBufObj;
+    glGenBuffers(1, &vertexBufObj);
+
+    glBindBuffer(GL_ARRAY_BUFFER, vertexBufObj);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertexShader, 1, &vertexShaderSrc, nullptr);
+    glCompileShader(vertexShader);
+
+    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(fragmentShader, 1, &fragmentShaderSrc, nullptr);
+    glCompileShader(fragmentShader);
+
+    GLuint shaderProgram = glCreateProgram();
+    glAttachShader(shaderProgram, vertexShader);
+    glAttachShader(shaderProgram, fragmentShader);
+    glLinkProgram(shaderProgram);
+    glUseProgram(shaderProgram);
+
+    GLint posAttribute = glGetAttribLocation(shaderProgram, "position");
+    glEnableVertexAttribArray(posAttribute);
+    glVertexAttribPointer(posAttribute, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
+}
+
+void OpenGL::drawSomething() {
+    glClearColor(0.0F, 0.0F, 0.0F, 1.0F);
+    glClear(GL_COLOR_BUFFER_BIT);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+    SDL_GL_SwapWindow(this->game->pWindow->window);
+}

src/graphics/opengl/opengl.h

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
+ * All rights reserved
+ */
+
+#ifndef _HOMD_GRAPHICS_GL
+#define _HOMD_GRAPHICS_GL
+
+#include <SDL2/SDL_video.h>
+#include <graphics/graphics.h>
+
+class Window;
+
+class OpenGL : public Graphics {
+    SDL_GLContext context = nullptr;
+
+   public:
+    OpenGL(Game*);
+    ~OpenGL() override = default;
+
+    void setGLContext();
+    void drawSomething() override;
+};
+
+#endif

src/scene/example/example.cpp

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
+ * All rights reserved
+ */
+
+#include <game/game.h>
+#include <graphics/graphics.h>
+#include <scene/example/example.h>
+
+Example::Example(Game* pGame) {
+    this->game = pGame;
+}
+
+void Example::draw() {
+    this->game->pRenderer->drawSomething();
+}

src/scene/example/example.h

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
+ * All rights reserved
+ */
+
+#include <scene/scene.h>
+
+class Example : public Scene {
+   public:
+    Example(Game*);
+    void draw() override;
+};

src/scene/scene.cpp

@@ -1,6 +0,0 @@
-/**
- * Copyright (c) 2023, Furkan Mudanyali <fmudanyali@icloud.com>
- * All rights reserved
- */
-
-#include <scene/scene.h>

src/scene/scene.h

@@ -6,11 +6,16 @@
 #ifndef _HOMD_SCENE
 #define _HOMD_SCENE
 
+class Game;
+
 class Scene {
    public:
+    Game* game;
+
     bool destroy = false;
     Scene() = default;
-    ~Scene() = default;
+    virtual ~Scene() = default;
+    virtual void draw() = 0;
 };
 
 #endif