scene: init returns the initial view transformation

src/demo/ballistics.cpp

@@ -16,13 +16,21 @@ namespace demo {
     draw_cube(writer, trans * translate(particle.position) * scale(1.f), color);
   }
 
-  void ballistics::init()
+  mat4x4 ballistics::init()
   {
     current_projectile_type = projectile_type::ARTILLERY;
 
     for (int i = 0; i < max_projectiles; i++) {
       projectiles[i].type = projectile_type::NONE;
     }
+
+    mat4x4 view_trans
+      = translate(vec3(-0.5, 0.5, 0.75))
+      * rotate_x(pi / 4)
+      * rotate_y(pi / 4)
+      * scale(vec3(-1, -1, 1));
+
+    return view_trans;
   }
 
   void ballistics::a()

src/demo/ballistics.hpp

@@ -29,7 +29,7 @@ namespace demo {
     projectile_type current_projectile_type;
     int32_t tick;
 
-    void init() override;
+    mat4x4 init() override;
     void a() override;
     void x() override;
     void update() override;

src/demo/scene.hpp

@@ -6,7 +6,7 @@
 namespace demo {
 
   struct scene {
-    virtual void init() = 0;
+    virtual mat4x4 init() = 0;
     virtual void a() {}
     virtual void b() {}
     virtual void x() {}

src/platform/graphics.cpp

@@ -104,7 +104,7 @@ namespace graphics {
     core_init();
     framebuffer::scaler_init();
 
-    current_scene->init();
+    view_trans = current_scene->init();
 
     // read
     while (spg_status::vsync(holly.SPG_STATUS));
@@ -144,17 +144,6 @@ namespace graphics {
                            1,
                            texture_memory_alloc.region_array.start,
                            texture_memory_alloc.object_list.start);
-
-    //vec3 t = {framebuffer::framebuffer.px_width / 2.f, framebuffer::framebuffer.px_height / 2.f, 0};
-    float s = framebuffer::framebuffer.px_height / 3.f;
-
-    view_trans
-      = scale(vec3(s, s, 1))
-      * translate(vec3(0, 0, 10))
-      * rotate_x(pi / 4)
-      * rotate_y(pi / 4)
-      * scale(vec3(-1, -1, 1));
-    view_trans = view_trans * translate(vec3(0, 0, -0.9));
   }
 
   void input_events()

src/platform/graphics_primitive.hpp

@@ -33,10 +33,11 @@ static inline vec3 screen_transform(const vec3& v)
 {
   float tx = framebuffer::framebuffer.px_width / 2.f;
   float ty = framebuffer::framebuffer.px_height / 2.f;
+  float s = framebuffer::framebuffer.px_height / 2.f;
 
-  float z = _fsrra(v.z - 9);
+  float z = _fsrra(v.z);
   float z2 = z * z;
-  return {v.x * z2 + tx , v.y * z2 + ty, z2};
+  return {(v.x) * s * z2 + tx , (v.y) * s * z2 + ty , z2};
 }
 
 static inline void draw_grid(ta_parameter_writer& writer,