Move camera logic to its own compilation unit.

Also remove unused shaders file.

src/camera.cpp

@@ -0,0 +1,74 @@
+#include <GL/glut.h>
+#include "camera.hpp"
+
+static float yaw, pitch;
+
+static struct {
+    float x, y, z;
+} camera;
+
+static void handleMouseMove(int x, int y)
+{
+    const float width = glutGet(GLUT_WINDOW_WIDTH) / 2;
+    const float height = glutGet(GLUT_WINDOW_HEIGHT) / 2;
+
+    yaw = (x - width) / width * 180;
+    pitch = (y - height) / height * 90;
+}
+
+static void handleKeys(unsigned char key, int, int)
+{
+    constexpr float rotationScaling = 0.2f;
+    constexpr float movementScaling = 0.2f;
+    switch (key) {
+        case 'a':
+            // TODO: handle rotations
+            camera.x += movementScaling;
+            break;
+
+        case 'd':
+            camera.x -= rotationScaling;
+            break;
+
+        case 'w':
+            camera.z += movementScaling;
+            break;
+
+        case 's':
+            camera.z -= movementScaling;
+            break;
+
+        case 'q':
+            // Utility quit function.
+            exit(0);
+
+        default:
+            // Do nothing.
+            break;
+    }
+}
+
+void fmri::registerCameraControls()
+{
+    resetCamera();
+    glutPassiveMotionFunc(handleMouseMove);
+    glutKeyboardFunc(handleKeys);
+}
+
+void fmri::resetCamera()
+{
+    camera.x = 0;
+    camera.y = 0;
+    camera.z = -10;
+
+    pitch = 0;
+    yaw = 0;
+}
+
+void fmri::configureCamera()
+{
+    glLoadIdentity();
+    glRotatef(yaw, 0, 1, 0);
+    glRotatef(pitch, 1, 0, 0);
+    glTranslatef(camera.x, camera.y, camera.z);
+}