From b315325f618691b9175c6df023f446d95f24ef1e Mon Sep 17 00:00:00 2001
From: Benjamin Palko <benjaminpalko@hotmail.com>
Date: Sun, 6 Oct 2024 10:37:44 -0400
Subject: [PATCH] setup tutorial code

---
 src/main.cpp | 75 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 59 insertions(+), 16 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index c2b6ac3..9724dab 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -49,7 +49,7 @@ void key_callback(GLFWwindow *window, int key, int scancode, int action,
   fmt::print("Key pressed {}\n", key_name);
 }
 
-int main() {
+int main(int argc, char *argv[]) {
 
   glfwSetErrorCallback(error_callback);
 
@@ -74,32 +74,75 @@ int main() {
     return -1;
   }
 
-  /*  GLEW  */
-  GLenum code = glewInit();
-  if (code != GLEW_OK) {
-    fmt::print("GLEW failed to init! {} - {}\n", code,
-               glewGetErrorString(code));
-    return -1;
-  }
-
   glfwSetKeyCallback(window, key_callback);
 
   glfwMakeContextCurrent(window);
   glfwSwapInterval(1);
 
-  /* Loop until the user closes the window */
+  /*  GLEW  */
+  GLenum err = glewInit();
+  if (err != GLEW_OK) {
+    fmt::print("GLEW failed to init! {}\n", err);
+    return -1;
+  }
+
+  GLuint vertex_buffer;
+  glGenBuffers(1, &vertex_buffer);
+  glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+  const GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
+  glCompileShader(vertex_shader);
+
+  const GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
+  glCompileShader(fragment_shader);
+
+  const GLuint program = glCreateProgram();
+  glAttachShader(program, vertex_shader);
+  glAttachShader(program, fragment_shader);
+  glLinkProgram(program);
+
+  const GLint mvp_location = glGetUniformLocation(program, "MVP");
+  const GLint vpos_location = glGetAttribLocation(program, "vPos");
+  const GLint vcol_location = glGetAttribLocation(program, "vCol");
+
+  GLuint vertex_array;
+  glGenVertexArrays(1, &vertex_array);
+  glBindVertexArray(vertex_array);
+  glEnableVertexAttribArray(vpos_location);
+  glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex),
+                        (void *)offsetof(Vertex, pos));
+  glEnableVertexAttribArray(vcol_location);
+  glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
+                        (void *)offsetof(Vertex, col));
+
   while (!glfwWindowShouldClose(window)) {
-    /* Render here */
+    int width, height;
+    glfwGetFramebufferSize(window, &width, &height);
+    const float ratio = width / (float)height;
+
+    glViewport(0, 0, width, height);
     glClear(GL_COLOR_BUFFER_BIT);
 
-    /* Swap front and back buffers */
-    glfwSwapBuffers(window);
+    mat4x4 m, p, mvp;
+    mat4x4_identity(m);
+    mat4x4_rotate_Z(m, m, (float)glfwGetTime());
+    mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
+    mat4x4_mul(mvp, p, m);
 
-    /* Poll for and process events */
+    glUseProgram(program);
+    glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat *)&mvp);
+    glBindVertexArray(vertex_array);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+
+    glfwSwapBuffers(window);
     glfwPollEvents();
   }
 
-  glfwTerminate();
+  glfwDestroyWindow(window);
 
-  return 0;
+  glfwTerminate();
+  exit(EXIT_SUCCESS);
 }