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hackthelobby/libcaca/caca/triangle.c

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/*
* libcaca Colour ASCII-Art library
* Copyright © 2002—2018 Sam Hocevar <sam@hocevar.net>
* All Rights Reserved
*
* This library is free software. It comes without any warranty, to
* the extent permitted by applicable law. You can redistribute it
* and/or modify it under the terms of the Do What the Fuck You Want
* to Public License, Version 2, as published by Sam Hocevar. See
* http://www.wtfpl.net/ for more details.
*/
/*
* This file contains triangle drawing functions, both filled and outline.
*/
#include "config.h"
#if !defined(__KERNEL__)
# include <stdlib.h>
#endif
#include "caca.h"
#include "caca_internals.h"
/** \brief Draw a triangle on the canvas using the given character.
*
* This function never fails.
*
* \param cv The handle to the libcaca canvas.
* \param x1 X coordinate of the first point.
* \param y1 Y coordinate of the first point.
* \param x2 X coordinate of the second point.
* \param y2 Y coordinate of the second point.
* \param x3 X coordinate of the third point.
* \param y3 Y coordinate of the third point.
* \param ch UTF-32 character to be used to draw the triangle outline.
* \return This function always returns 0.
*/
int caca_draw_triangle(caca_canvas_t * cv, int x1, int y1, int x2, int y2,
int x3, int y3, uint32_t ch)
{
caca_draw_line(cv, x1, y1, x2, y2, ch);
caca_draw_line(cv, x2, y2, x3, y3, ch);
caca_draw_line(cv, x3, y3, x1, y1, ch);
return 0;
}
/** \brief Draw a thin triangle on the canvas.
*
* This function never fails.
*
* \param cv The handle to the libcaca canvas.
* \param x1 X coordinate of the first point.
* \param y1 Y coordinate of the first point.
* \param x2 X coordinate of the second point.
* \param y2 Y coordinate of the second point.
* \param x3 X coordinate of the third point.
* \param y3 Y coordinate of the third point.
* \return This function always returns 0.
*/
int caca_draw_thin_triangle(caca_canvas_t * cv, int x1, int y1,
int x2, int y2, int x3, int y3)
{
caca_draw_thin_line(cv, x1, y1, x2, y2);
caca_draw_thin_line(cv, x2, y2, x3, y3);
caca_draw_thin_line(cv, x3, y3, x1, y1);
return 0;
}
/** \brief Fill a triangle on the canvas using the given character.
*
* This function never fails.
*
* \param cv The handle to the libcaca canvas.
* \param x1 X coordinate of the first point.
* \param y1 Y coordinate of the first point.
* \param x2 X coordinate of the second point.
* \param y2 Y coordinate of the second point.
* \param x3 X coordinate of the third point.
* \param y3 Y coordinate of the third point.
* \param ch UTF-32 character to be used to fill the triangle.
* \return This function always returns 0.
*/
int caca_fill_triangle(caca_canvas_t * cv, int x1, int y1, int x2, int y2,
int x3, int y3, uint32_t ch)
{
int x, y, xmin, xmax, ymin, ymax;
int xx1, xx2, xa, xb, sl21, sl31, sl32;
/* Bubble-sort y1 <= y2 <= y3 */
if (y1 > y2)
return caca_fill_triangle(cv, x2, y2, x1, y1, x3, y3, ch);
if (y2 > y3)
return caca_fill_triangle(cv, x1, y1, x3, y3, x2, y2, ch);
/* Compute slopes and promote precision */
sl21 = (y2 == y1) ? 0 : (x2 - x1) * 0x10000 / (y2 - y1);
sl31 = (y3 == y1) ? 0 : (x3 - x1) * 0x10000 / (y3 - y1);
sl32 = (y3 == y2) ? 0 : (x3 - x2) * 0x10000 / (y3 - y2);
x1 *= 0x10000;
x2 *= 0x10000;
x3 *= 0x10000;
ymin = y1 < 0 ? 0 : y1;
ymax = y3 + 1 < cv->height ? y3 + 1 : cv->height;
if (ymin < y2)
{
xa = x1 + sl21 * (ymin - y1);
xb = x1 + sl31 * (ymin - y1);
}
else if (ymin == y2)
{
xa = x2;
xb = (y1 == y3) ? x3 : x1 + sl31 * (ymin - y1);
}
else /* (ymin > y2) */
{
xa = x3 + sl32 * (ymin - y3);
xb = x3 + sl31 * (ymin - y3);
}
/* Rasterize our triangle */
for (y = ymin; y < ymax; y++)
{
/* Rescale xa and xb, recentering the division */
if (xa < xb)
{
xx1 = (xa + 0x800) / 0x10000;
xx2 = (xb + 0x801) / 0x10000;
}
else
{
xx1 = (xb + 0x800) / 0x10000;
xx2 = (xa + 0x801) / 0x10000;
}
xmin = xx1 < 0 ? 0 : xx1;
xmax = xx2 + 1 < cv->width ? xx2 + 1 : cv->width;
for (x = xmin; x < xmax; x++)
caca_put_char(cv, x, y, ch);
xa += y < y2 ? sl21 : sl32;
xb += sl31;
}
return 0;
}
/* This function actually renders the triangle, but is not exported due to
sam's pedantic will. */
static int caca_fill_triangle_textured_l(caca_canvas_t * cv,
int x1, int y1,
int x2, int y2,
int x3, int y3,
caca_canvas_t * tex,
float u1, float v1,
float u2, float v2,
float u3, float v3)
{
float y2y1, y3y1, y3y2;
float sl12, sl13, sl23;
float usl12, usl13, usl23, vsl12, vsl13, vsl23;
float xa, xb, ua, va, ub, vb, u, v;
uint32_t savedattr;
int tw, th, x, y, s;
#define SWAP_F(a, b) {float c = a; a = b; b = c; }
/* (very) Naive and (very) float-based affine and (very) non-clipped and
(very) non-corrected triangle mapper Accepts arbitrary texture sizes
Coordinates clamped to [0.0 - 1.0] (no repeat) */
if (!cv || !tex)
return -1;
/* Bubble-sort y1 <= y2 <= y3 */
if (y1 > y2)
return caca_fill_triangle_textured_l(cv,
x2, y2, x1, y1, x3, y3,
tex, u2, v2, u1, v1, u3, v3);
if (y2 > y3)
return caca_fill_triangle_textured_l(cv,
x1, y1, x3, y3, x2, y2,
tex, u1, v1, u3, v3, u2, v2);
savedattr = caca_get_attr(cv, -1, -1);
/* Clip texture coordinates */
if (u1 < 0.0f) u1 = 0.0f; else if (u1 > 1.0f) u1 = 1.0f;
if (u2 < 0.0f) u2 = 0.0f; else if (u2 > 1.0f) u2 = 1.0f;
if (u3 < 0.0f) u3 = 0.0f; else if (u3 > 1.0f) u3 = 1.0f;
if (v1 < 0.0f) v1 = 0.0f; else if (v1 > 1.0f) v1 = 1.0f;
if (v2 < 0.0f) v2 = 0.0f; else if (v2 > 1.0f) v2 = 1.0f;
if (v3 < 0.0f) v3 = 0.0f; else if (v3 > 1.0f) v3 = 1.0f;
/* Convert relative tex coordinates to absolute */
tw = caca_get_canvas_width(tex);
th = caca_get_canvas_height(tex);
u1 *= (float)tw;
u2 *= (float)tw;
u3 *= (float)tw;
v1 *= (float)th;
v2 *= (float)th;
v3 *= (float)th;
y2y1 = (float)(y2 - y1);
y3y1 = (float)(y3 - y1);
y3y2 = (float)(y3 - y2);
/* Compute slopes, making sure we don't divide by zero */
/* (in this case, we don't need the value anyway) */
/* FIXME : only compute needed slopes */
sl12 = ((float)x2 - x1) / (y2y1 == 0 ? 1 : y2y1);
sl13 = ((float)x3 - x1) / (y3y1 == 0 ? 1 : y3y1);
sl23 = ((float)x3 - x2) / (y3y2 == 0 ? 1 : y3y2);
usl12 = (u2 - u1) / (y2y1 == 0 ? 1 : y2y1);
usl13 = (u3 - u1) / (y3y1 == 0 ? 1 : y3y1);
usl23 = (u3 - u2) / (y3y2 == 0 ? 1 : y3y2);
vsl12 = (v2 - v1) / (y2y1 == 0 ? 1 : y2y1);
vsl13 = (v3 - v1) / (y3y1 == 0 ? 1 : y3y1);
vsl23 = (v3 - v2) / (y3y2 == 0 ? 1 : y3y2);
xa = (float)x1;
xb = (float)x1;
ua = u1; ub = u1;
va = v1; vb = v1;
s = 0;
/* Top */
for (y = y1; y < y2; y++)
{
float tus, tvs;
if (xb < xa)
{
SWAP_F(xb, xa);
SWAP_F(sl13, sl12);
SWAP_F(ua, ub);
SWAP_F(va, vb);
SWAP_F(usl13, usl12);
SWAP_F(vsl13, vsl12);
s = 1;
}
tus = (ub - ua) / (xb - xa);
tvs = (vb - va) / (xb - xa);
v = va;
u = ua;
/* scanline */
for (x = xa; x < xb; x++)
{
uint32_t attr, c;
u += tus;
v += tvs;
/* FIXME: use caca_get_canvas_attrs / caca_get_canvas_chars */
attr = caca_get_attr(tex, u, v);
c = caca_get_char(tex, u, v);
caca_set_attr(cv, attr);
caca_put_char(cv, x, y, c);
}
xa += sl13;
xb += sl12;
ua += usl13;
va += vsl13;
ub += usl12;
vb += vsl12;
}
if (s)
{
SWAP_F(xb, xa);
SWAP_F(sl13, sl12);
SWAP_F(ua, ub);
SWAP_F(va, vb);
SWAP_F(usl13, usl12);
SWAP_F(vsl13, vsl12);
}
/* Bottom */
xb = (float)x2;
/* These variables are set by 'top' routine and are in an incorrect state
if we only draw the bottom part */
if (y1 == y2)
{
ua = u1;
ub = u2;
va = v1;
vb = v2;
}
for (y = y2; y < y3; y++)
{
float tus, tvs;
if (xb <= xa)
{
SWAP_F(xb, xa);
SWAP_F(sl13, sl23);
SWAP_F(ua, ub);
SWAP_F(va, vb);
SWAP_F(usl13, usl23);
SWAP_F(vsl13, vsl23);
}
tus = (ub - ua) / ((float)xb - xa);
tvs = (vb - va) / ((float)xb - xa);
u = ua;
v = va;
/* scanline */
for (x = xa; x < xb; x++)
{
uint32_t attr, c;
u += tus;
v += tvs;
/* FIXME, can be heavily optimised */
attr = caca_get_attr(tex, u, v);
c = caca_get_char(tex, u, v);
caca_set_attr(cv, attr);
caca_put_char(cv, x, y, c);
}
xa += sl13;
xb += sl23;
ua += usl13;
va += vsl13;
ub += usl23;
vb += vsl23;
}
caca_set_attr(cv, savedattr);
return 0;
}
/** \brief Fill a triangle on the canvas using an arbitrary-sized texture.
*
* This function fails if one or both the canvas are missing
*
* \param cv The handle to the libcaca canvas.
* \param coords The coordinates of the triangle (3{x,y})
* \param tex The handle of the canvas texture.
* \param uv The coordinates of the texture (3{u,v})
* \return This function return 0 if ok, -1 if canvas or texture are missing.
*/
int caca_fill_triangle_textured(caca_canvas_t * cv,
int coords[6],
caca_canvas_t * tex, float uv[6])
{
return caca_fill_triangle_textured_l(cv,
coords[0], coords[1],
coords[2], coords[3],
coords[4], coords[5],
tex,
uv[0], uv[1],
uv[2], uv[3], uv[4], uv[5]);
}
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