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2-pt perspective -- add more guides

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This commit is contained in:
Bill Kendrick 2023-12-21 12:07:55 -08:00
parent 05b76c8b5f
commit 9cc4e80d98
1 changed files with 50 additions and 0 deletions
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50
magic/src/n_pt_persp.c
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@ -380,6 +380,56 @@ void n_pt_persp_drag(magic_api * api, int which,
api->line((void *) api, which, canvas, NULL,
x, y, a1_pt_x, a1_pt_y, 12,
n_pt_persp_line_xor_callback);
} else if (which == TOOL_2PT_DRAW) {
/* 2-point perspective */
int i, x1, y1, x2, y2;
float slope;
/* Horizon line (vanishing point) */
slope = ((float) a2_pt_y[0] - (float) a2_pt_y[1]) / ((float) a2_pt_x[0] - (float) a2_pt_x[1]);
x1 = 0;
y1 = a2_pt_y[0] - (a2_pt_x[0] * slope);
x2 = canvas->w;
y2 = a2_pt_y[0] + ((canvas->w - a2_pt_x[0]) * slope);
api->line((void *) api, which, canvas, NULL,
x1, y1, x2, y2, 12,
n_pt_persp_line_xor_callback);
/* Horizon line (from the cursor) */
x1 = 0;
y1 = y - (x * slope);
x2 = canvas->w;
y2 = y + ((canvas->w - x) * slope);
api->line((void *) api, which, canvas, NULL,
x1, y1, x2, y2, 12,
n_pt_persp_line_xor_callback);
/* Perpendicular-to-horizon line (from the cursor) */
if (slope == 0.0 || slope == M_PI) {
x1 = x;
y1 = 0;
x2 = x;
y2 = canvas->h;
} else {
float perp_slope = -(slope);
x1 = x - (y * perp_slope);
y1 = 0;
x2 = x + ((canvas->h - y) * perp_slope);
y2 = canvas->h;
}
api->line((void *) api, which, canvas, NULL,
x1, y1, x2, y2, 12,
n_pt_persp_line_xor_callback);
/* Diagonal lines from cursor to the vanishing points */
for (i = 0; i < 2; i++) {
api->line((void *) api, which, canvas, NULL,
x, y, a2_pt_x[i], a2_pt_y[i], 12,
n_pt_persp_line_xor_callback);
}
}
}