Convert OpenGL triangle example to C99

examples/simple.c

@@ -76,10 +76,6 @@ static void key_callback(GLFWwindow* window, int key, int scancode, int action,
 
 int main(void)
 {
-    GLFWwindow* window;
-    GLuint vertex_buffer, vertex_shader, fragment_shader, program;
-    GLint mvp_location, vpos_location, vcol_location;
-
     glfwSetErrorCallback(error_callback);
 
     if (!glfwInit())
@@ -88,7 +84,7 @@ int main(void)
     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
 
-    window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
+    GLFWwindow* window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
     if (!window)
     {
         glfwTerminate();
@@ -103,26 +99,27 @@ int main(void)
 
     // NOTE: OpenGL error checks have been omitted for brevity
 
+    GLuint vertex_buffer;
     glGenBuffers(1, &vertex_buffer);
     glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
-    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+    const GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
     glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
     glCompileShader(vertex_shader);
 
-    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+    const GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
     glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
     glCompileShader(fragment_shader);
 
-    program = glCreateProgram();
+    const GLuint program = glCreateProgram();
     glAttachShader(program, vertex_shader);
     glAttachShader(program, fragment_shader);
     glLinkProgram(program);
 
-    mvp_location = glGetUniformLocation(program, "MVP");
+    const GLint mvp_location = glGetUniformLocation(program, "MVP");
-    vpos_location = glGetAttribLocation(program, "vPos");
+    const GLint vpos_location = glGetAttribLocation(program, "vPos");
-    vcol_location = glGetAttribLocation(program, "vCol");
+    const GLint vcol_location = glGetAttribLocation(program, "vCol");
 
     glEnableVertexAttribArray(vpos_location);
     glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
@@ -133,16 +130,14 @@ int main(void)
 
     while (!glfwWindowShouldClose(window))
     {
-        float ratio;
         int width, height;
-        mat4x4 m, p, mvp;
-
         glfwGetFramebufferSize(window, &width, &height);
-        ratio = width / (float) height;
+        const float ratio = width / (float) height;
 
         glViewport(0, 0, width, height);
         glClear(GL_COLOR_BUFFER_BIT);
 
+        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);