Rendering

ZX Rendering Techniques

Camera Systems

All camera state in static variables for rollback safety.

Camera FFI

Follow Camera (Core)

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.

Basic Stencil Flow

// 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

Particle System Core

#[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);
    set_color(0xFFFFFFFF);
    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);
            push_identity();
        }
    }
}

Custom Fonts

let tex = rom_texture_str("pixel_font");
let font = load_font(tex, 8, 12, 32, 96);  // 8x12 glyphs

// In render:
font_bind(font);
set_color(0xFFFFFFFF);
draw_text_str("SCORE", 10.0, 10.0, 24.0);
font_bind(0);  // Back to default

Coordinate Convention

Y-up, right-handed, -Z forward. When yaw=0, camera looks toward -Z.