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#include <fitz.h>
typedef struct fz_vertex
{
float x, y;
float l;
} fz_vertex;
typedef struct fz_triangle
{
fz_vertex vertex[3];
} fz_triangle;
#define putpixel(x, y, c) \
if (x >= 0 && x < dstp->w && y >= 0 && y < dstp->h) { \
dstp->samples[((x)+(y)*(dstp->w))*4+0] = 255; \
dstp->samples[((x)+(y)*(dstp->w))*4+1] = c[0]; \
dstp->samples[((x)+(y)*(dstp->w))*4+2] = c[1]; \
dstp->samples[((x)+(y)*(dstp->w))*4+3] = c[2]; \
} \
void fz_swapvertex(fz_vertex *a, fz_vertex *b)
{
fz_vertex temp;
temp = *a;
*a = *b;
*b = temp;
}
fz_error *
fz_drawgouraudtriangle(fz_triangle triangle, fz_pixmap *dstp, int destcol[512][4],
int bx0, int by0, int bx1, int by1)
{
fz_error *error;
fz_vertex a, b, c;
a = triangle.vertex[0];
b = triangle.vertex[1];
c = triangle.vertex[2];
/* need more accurate clipping method */
{
fz_rect bb1;
fz_rect bb2;
bb1.min.x = MIN(MIN(a.x, b.x), c.x);
bb1.min.y = MIN(MIN(a.y, b.y), c.y);
bb1.max.x = MAX(MAX(a.x, b.x), c.x);
bb1.max.y = MAX(MAX(a.y, b.y), c.y);
bb2.min.x = bx0;
bb2.min.y = by0;
bb2.max.x = bx1;
bb2.max.y = by1;
if (fz_isemptyrect(fz_intersectrects(bb1, bb2)))
return nil;
}
if(a.y > b.y) fz_swapvertex(&a, &b);
if(a.y > c.y) fz_swapvertex(&a, &c);
if(b.y > c.y) fz_swapvertex(&b, &c);
float diff_y = (b.y - a.y);
float slopeab_x = (b.x - a.x) / diff_y;
float slopeab_l = (b.l - a.l) / diff_y;
float xab = a.x;
float lab = a.l;
diff_y = (c.y - a.y);
float slopeac_x = (c.x - a.x) / diff_y;
float slopeac_l = (c.l - a.l) / diff_y;
float xac = a.x;
float lac = a.l;
int maxy = (int)(b.y);
int incx;
int y;
for(y = (int)(a.y); y < maxy; y++)
{
int maxx = (int)(xac);
if(xab < xac) incx = 1;
else incx = -1;
float diff_x = (xac - xab) * incx;
float slope_l = (lac - lab) / diff_x;
float l = lab;
for(int x = (int)(xab); x != maxx+incx; x += incx)
{
if (l < 0) l = 0;
if (l > 511) l = 511;
putpixel(x, y, destcol[(int)(l)]);
l += slope_l;
}
xab += slopeab_x;
lab += slopeab_l;
xac += slopeac_x;
lac += slopeac_l;
}
diff_y = (c.y - b.y);
float slopebc_x = (c.x - b.x) / diff_y;
float slopebc_l = (c.l - b.l) / diff_y;
float xbc = b.x;
float lbc = b.l;
maxy = (int)(c.y);
for(; y < maxy; y++)
{
int maxx = (int)(xac);
if(xbc < xac) incx = 1;
else incx = -1;
float diff_x = (xac - xbc) * incx;
float slope_l = (lac - lbc) / diff_x;
float l = lbc;
for(int x = (int)(xbc); x != maxx+incx; x += incx)
{
if (l < 0) l = 0;
if (l > 511) l = 511;
putpixel(x, y, destcol[(int)(l)]);
l += slope_l;
}
xac += slopeac_x;
lac += slopeac_l;
xbc += slopebc_x;
lbc += slopebc_l;
}
return nil;
}
fz_error *
fz_rendershade(fz_shade *shade, fz_matrix ctm, fz_colorspace *dsts, fz_pixmap *dstp)
{
int x, y;
fz_triangle triangle;
fz_point point;
int destcol[512][4];
for (int i=0; i<512; ++i) {
float col[4];
shade->colorspace->convcolor(shade->colorspace,
shade->function[i], dsts, col);
for (int j=0; j<3; ++j) {
destcol[i][j] = col[j] * 255;
}
}
if (!shade) return nil;
ctm = fz_concat(shade->matrix, ctm);
ctm = fz_concat(ctm, fz_translate(-dstp->x, -dstp->y));
int ncomp = shade->meshcap;
for (int i=0; i<shade->meshlen; ++i) {
for (int j=0; j<3; ++j) {
point.x = shade->mesh[(i*3+j)*3+0];
point.y = shade->mesh[(i*3+j)*3+1];
point = fz_transformpoint(ctm, point);
triangle.vertex[j].x = point.x;
triangle.vertex[j].y = point.y;
triangle.vertex[j].l = shade->mesh[(i*3+j)*3+2];
}
fz_drawgouraudtriangle(triangle, dstp, destcol, 0, 0, dstp->w, dstp->h);
}
return nil;
}
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