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//! Render module entrypoints
//! Render modules only get an entry point, so not much needed here
//! other than necessary type definitions.

use bytemuck::Pod;
use bytemuck::Zeroable;

/// `ark_render_frame` - Render a frame with a set of instances to draw
///
/// # Example
///
/// ```no_run
/// pub use ark_api_ffi::entrypoints::render::{RenderFrameInfo, RenderDrawInfo};
/// #[no_mangle]
/// pub unsafe fn ark_render_frame(frame_info_ptr: *const RenderFrameInfo, draw_info_ptr: *const RenderDrawInfo, draw_info_len: u32) {
/// }
pub type RenderFrameFn = fn(
    frame_info_ptr: *const RenderFrameInfo,
    draw_info_ptr: *const RenderDrawInfo,
    draw_info_len: u32,
);
pub const RENDER_FRAME: &str = "ark_render_frame";

bitflags! {
    #[repr(C)]
    #[derive(Pod, Zeroable)]
    pub struct RenderDrawFlags : u32 {
        const REMOVED = 0b0000_0001;
    }
}

/// Raw struct, abstracted away by the impl macro so not accessed directly by user code.
#[derive(Copy, Clone, Pod, Zeroable)]
#[repr(C)]
pub struct RenderDrawInfo {
    pub object_to_world: [f32; 16],
    pub static_data_ptr: u32,
    pub static_data_len: u32,
    /// Stable instance ID for identifying an instance across frames.
    pub cache_id: u64,

    pub flags: RenderDrawFlags,

    pub dynamic_data_ptr: u32,
    pub dynamic_data_len: u32,

    // Unlike in RenderFrameInfo, we need to reserve space here for any future expantion
    // because we pass as slice `RenderDrawInfo` to the module so the size is fixed.
    // Running out of reserved space already...
    pub reserved: u32,
}

/// General information about the current frame.
///
/// `view_to_world` is useful for making camera aligned things in world space,
/// such as particles.
/// Use `game_time_s` and `frame_delta_times_s` to drive animations, as appropriate.
/// Will be approximately in sync with the simulated game time on the server,
/// but will have higher resolution in time if you are running on a high refresh rate monitor.
#[derive(Copy, Clone, Pod, Zeroable)]
#[repr(C)]
pub struct RenderFrameInfo {
    pub view_to_world: [f32; 16],
    pub game_time_s: f64,
    pub frame_delta_time_s: f32,
    pub display_width: u16,
    pub display_height: u16,
    pub dpi_factor: f32,
    pub _pad: u32,
    // Can safely be (strictly) expanded without breaking ABI
}