// 3D -> 2D projection and frustum classification.
//
// Uses a 90 deg horizontal/vertical FOV (matching the original FS2
// frustum) and the Apple II hires viewport (280 wide, rows 0..98).
// All camera-space coordinates are Q16.16 world-units (matching
// `CameraT::worldX/Y/Z`); screen output is integer pixels.

#ifndef PROJECTION_H
#define PROJECTION_H

#include <stdbool.h>
#include <stdint.h>
#include "types.h"

typedef struct ProjectedT {
        int32_t  cx;            // camera-space X (Q16.16 world units)
        int32_t  cy;            // camera-space Y
        int32_t  cz;            // camera-space Z (positive = in front)
        int16_t  screenX;       // post-projection screen column
        int16_t  screenY;       // post-projection screen row
        uint8_t  outcode;       // OUTCODE_* bits
} ProjectedT;

// Compute frustum outcodes for a camera-space point (Q16.16).
uint8_t projectionOutcode(int32_t cx_q1616, int32_t cy_q1616, int32_t cz_q1616);

// Project a camera-space point onto the screen. Returns true if the
// point is visible (outcode == 0). When false, screenX / screenY are
// undefined.
bool projectionToScreen(int32_t cx_q1616, int32_t cy_q1616, int32_t cz_q1616, int16_t *outX, int16_t *outY);

// Trivial-reject + trivial-accept Cohen-Sutherland clip in 3D.
// On entry both endpoints are camera-space + outcode-stamped. On
// exit, if true, the endpoints have been moved onto the visible
// region of the frustum. Returns false if the line is wholly
// outside.
bool projectionClipLine(ProjectedT *a, ProjectedT *b);

#endif