ZX Rendering Techniques
Camera Systems
All camera state in static variables for rollback safety.
Camera FFI
| Function | Purpose |
|---|---|
camera_set(x,y,z, tx,ty,tz) | Position + look-at |
camera_fov(degrees) | Field of view (default 60) |
Follow Camera (Core)
rust
static mut CAM_X: f32 = 0.0;
static mut CAM_Y: f32 = 5.0;
static mut CAM_Z: f32 = 10.0;
fn update_follow_camera(tx: f32, ty: f32, tz: f32) {
let dt = delta_time();
let t = (5.0 * dt).min(1.0);
unsafe {
CAM_X += (tx - CAM_X) * t;
CAM_Y += (ty + 5.0 - CAM_Y) * t;
CAM_Z += (tz + 10.0 - CAM_Z) * t;
}
}
Render Passes & Stencil
Create portals, scopes, masks using render passes.
| Function | Purpose |
|---|---|
begin_pass(clear_depth) | New pass |
begin_pass_stencil_write(ref, clear) | Create mask |
begin_pass_stencil_test(ref, clear) | Render in mask |
Basic Stencil Flow
rust
// 1. Create mask begin_pass_stencil_write(1, 0); draw_circle(SCREEN_CX, SCREEN_CY, 200.0); // 2. Render inside mask begin_pass_stencil_test(1, 0); draw_scene(); // 3. Return to normal begin_pass(0);
Billboard Particles
| Function | Mode | Use |
|---|---|---|
draw_billboard(w, h, 1, color) | Spherical | Particles |
draw_billboard(w, h, 2, color) | Cylindrical | Trees |
Particle System Core
rust
#[derive(Copy, Clone, Default)]
struct Particle { x: f32, y: f32, z: f32, vx: f32, vy: f32, vz: f32, life: f32 }
static mut PARTICLES: [Particle; 256] = [...];
fn render_particles(tex: u32) {
texture_bind(tex);
for p in unsafe { PARTICLES.iter() } {
if p.life > 0.0 {
push_translate(p.x, p.y, p.z);
draw_billboard(1.0, 1.0, 1, 0xFFFFFFFF);
push_identity();
}
}
}
Custom Fonts
rust
let tex = rom_texture_str("pixel_font");
let font = load_font(tex, 8, 12, 32, 96); // 8x12 glyphs
// In render:
font_bind(font);
draw_text_str("SCORE", 10.0, 10.0, 24.0, 0xFFFFFFFF);
font_bind(0); // Back to default
Coordinate Convention
Y-up, right-handed, -Z forward. When yaw=0, camera looks toward -Z.