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bumptri.c
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#include "bumptri.h"
#define SHIFT_CONST 6
static void swap_vertex(vertex_t* v1, vertex_t* v2)
{
int swap;
unsigned char swapc;
swap = v1->x;
v1->x = v2->x;
v2->x = swap;
swap = v1->y;
v1->y = v2->y;
v2->y = swap;
swap = v1->tx;
v1->tx = v2->tx;
v2->tx = swap;
swap = v1->ty;
v1->ty = v2->ty;
v2->ty = swap;
swapc = v1->c;
v1->c = v2->c;
v2->c = swap;
}
static void reorder_vertices(vertex_t* v1, vertex_t* v2, vertex_t* v3)
{
if (v1->y > v2->y) {
swap_vertex(v1, v2);
}
if (v2->y > v3->y) {
swap_vertex(v2, v3);
}
if (v1->y > v2->y) {
swap_vertex(v1, v2);
}
}
static void flat_line(int x1, int x2, int y, unsigned char color,
unsigned char* buffer)
{
int i;
unsigned char* ofs;
if (y < 0 || y > 199 || x1 == x2) {
return;
}
if (x1 > x2) {
i = x1;
x1 = x2;
x2 = i;
}
ofs = buffer;
ofs += ((y << 6) + (y << 8) + x1);
i = 0;
while ((i++) < (x2 - x1)) {
*ofs = color;
ofs++;
}
}
void flat_triangle(vertex_t* v1, vertex_t* v2, vertex_t* v3, unsigned char color, unsigned char* buffer)
{
long dx12, dx13, dx23, scan_x1, scan_x2;
int y, dy;
reorder_vertices(v1, v2, v3);
dy = v2->y - v1->y;
if (dy != 0) {
dx12 = ((v2->x - v1->x) << SHIFT_CONST) / dy;
}
else {
dx12 = 0;
}
dy = v3->y - v1->y;
if (dy != 0) {
dx13 = ((v3->x - v1->x) << SHIFT_CONST) / dy;
}
else {
dx13 = 0;
}
dy = v3->y - v2->y;
if (dy != 0) {
dx23 = ((v3->x - v2->x) << SHIFT_CONST) / dy;
}
else {
dx23 = 0;
}
scan_x1 = scan_x2 = v1->x << SHIFT_CONST;
for (y = v1->y; y < v2->y; y++) {
flat_line(scan_x1 >> SHIFT_CONST,
scan_x2 >> SHIFT_CONST, y, color, buffer);
scan_x1 += dx13;
scan_x2 += dx12;
}
scan_x2 = v2->x << SHIFT_CONST;
for (y = v2->y; y < v3->y; y++) {
flat_line(scan_x1 >> SHIFT_CONST,
scan_x2 >> SHIFT_CONST, y, color, buffer);
scan_x1 += dx13;
scan_x2 += dx23;
}
}
static void gouraud_line(int x1, int x2, int y, unsigned char c1, unsigned char c2,
unsigned char* buffer)
{
long delta_c, curr_c;
int i;
unsigned char* ofs;
if (y < 0 || y > 199 || x1 == x2) {
return;
}
if (x1 > x2) {
i = x1;
x1 = x2;
x2 = i;
i = c1;
c1 = c2;
c2 = i;
}
if (x1 > 319 || x2 < 0) {
return;
}
delta_c = ((c2 - c1) << SHIFT_CONST) / (x2 - x1);
curr_c = c1 << SHIFT_CONST;
if (x1 < 0) {
curr_c += (-x1) * delta_c;
x1 = 0;
}
if (x2 > 319) {
x2 = 319;
}
ofs = buffer;
ofs += ((y << 6) + (y << 8) + x1);
i = 0;
while ((i++) < (x2 - x1)) {
*ofs = curr_c >> SHIFT_CONST;
curr_c += delta_c;
ofs++;
}
}
void gouraud_triangle(vertex_t* v1, vertex_t* v2, vertex_t* v3, unsigned char* buffer)
{
long dx12, dx13, dx23, scan_x1, scan_x2;
long dc12, dc13, dc23, scan_c1, scan_c2;
int y, dy;
reorder_vertices(v1, v2, v3);
dy = v2->y - v1->y;
if (dy != 0) {
dx12 = ((v2->x - v1->x) << SHIFT_CONST) / dy;
dc12 = ((v2->c - v1->c) << SHIFT_CONST) / dy;
}
else {
dx12 = 0;
dc12 = 0;
}
dy = v3->y - v1->y;
if (dy != 0) {
dx13 = ((v3->x - v1->x) << SHIFT_CONST) / dy;
dc13 = ((v3->c - v1->c) << SHIFT_CONST) / dy;
}
else {
dx13 = 0;
dc13 = 0;
}
dy = v3->y - v2->y;
if (dy != 0) {
dx23 = ((v3->x - v2->x) << SHIFT_CONST) / dy;
dc23 = ((v3->c - v2->c) << SHIFT_CONST) / dy;
}
else {
dx23 = 0;
dc23 = 0;
}
scan_x1 = scan_x2 = v1->x << SHIFT_CONST;
scan_c1 = scan_c2 = v1->c << SHIFT_CONST;
for (y = v1->y; y < v2->y; y++) {
gouraud_line(scan_x1 >> SHIFT_CONST, scan_x2 >> SHIFT_CONST, y,
scan_c1 >> SHIFT_CONST, scan_c2 >> SHIFT_CONST, buffer);
scan_x1 += dx13;
scan_x2 += dx12;
scan_c1 += dc13;
scan_c2 += dc12;
}
scan_x2 = v2->x << SHIFT_CONST;
scan_c2 = v2->c << SHIFT_CONST;
for (y = v2->y; y < v3->y; y++) {
gouraud_line(scan_x1 >> SHIFT_CONST, scan_x2 >> SHIFT_CONST, y,
scan_c1 >> SHIFT_CONST, scan_c2 >> SHIFT_CONST, buffer);
scan_x1 += dx13;
scan_x2 += dx23;
scan_c1 += dc13;
scan_c2 += dc23;
}
}
static void textured_line(int x1, int x2, int y,
int tx1, int ty1, int tx2, int ty2,
int shifty, unsigned char* texture, unsigned char* buffer)
{
long delta_x, delta_y, curr_x, curr_y;
int i, lenght;
unsigned char* ofs;
if (y < 0 || y > 199 || x1 == x2) {
return;
}
if (x1 > x2) {
i = x1;
x1 = x2;
x2 = i;
i = tx1;
tx1 = tx2;
tx2 = i;
i = ty1;
ty1 = ty2;
ty2 = i;
}
lenght = x2 - x1;
delta_x = ((tx2 - tx1) << SHIFT_CONST) / lenght;
curr_x = tx1 << SHIFT_CONST;
delta_y = ((ty2 - ty1) << SHIFT_CONST) / lenght;
curr_y = ty1 << SHIFT_CONST;
if (x1 < 0) {
curr_x += (-x1) * delta_x;
curr_y += (-x1) * delta_y;
x1 = 0;
}
if (x2 > 319) {
x2 = 319;
}
ofs = buffer;
ofs += ((y << 6) + (y << 8) + x1);
for (i = x1; i < x2; i++) {
*ofs = texture[(curr_x >> SHIFT_CONST) + ((curr_y >> SHIFT_CONST) << shifty)];
ofs++;
curr_x += delta_x;
curr_y += delta_y;
}
}
void textured_triangle(vertex_t* v1, vertex_t* v2, vertex_t* v3, int shifty, unsigned char* texture, unsigned char* buffer)
{
long dx12, dx13, dx23, curr_x1, curr_x2;
long tdx12, tdy12, tdx13, tdy13, tdx23, tdy23, scan_x1, scan_y1, scan_x2, scan_y2;
int y, dy;
reorder_vertices(v1, v2, v3);
dy = v2->y - v1->y;
if (dy != 0) {
dx12 = ((v2->x - v1->x) << SHIFT_CONST) / dy;
tdx12 = ((v2->tx - v1->tx) << SHIFT_CONST) / dy;
tdy12 = ((v2->ty - v1->ty) << SHIFT_CONST) / dy;
}
else {
dx12 = 0;
tdx12 = 0;
tdy12 = 0;
}
dy = v3->y - v1->y;
if (dy != 0) {
dx13 = ((v3->x - v1->x) << SHIFT_CONST) / dy;
tdx13 = ((v3->tx - v1->tx) << SHIFT_CONST) / dy;
tdy13 = ((v3->ty - v1->ty) << SHIFT_CONST) / dy;
}
else {
dx13 = 0;
tdx13 = 0;
tdy13 = 0;
}
dy = v3->y - v2->y;
if (dy != 0) {
dx23 = ((v3->x - v2->x) << SHIFT_CONST) / dy;
tdx23 = ((v3->tx - v2->tx) << SHIFT_CONST) / dy;
tdy23 = ((v3->ty - v2->ty) << SHIFT_CONST) / dy;
}
else {
dx23 = 0;
tdx23 = 0;
tdy23 = 0;
}
curr_x1 = curr_x2 = v1->x << SHIFT_CONST;
scan_x1 = scan_x2 = v1->tx << SHIFT_CONST;
scan_y1 = scan_y2 = v1->ty << SHIFT_CONST;
for (y = v1->y; y < v2->y; y++) {
textured_line(curr_x1 >> SHIFT_CONST, curr_x2 >> SHIFT_CONST, y,
scan_x1 >> SHIFT_CONST, scan_y1 >> SHIFT_CONST,
scan_x2 >> SHIFT_CONST, scan_y2 >> SHIFT_CONST, shifty, texture, buffer);
curr_x1 += dx13;
curr_x2 += dx12;
scan_x1 += tdx13;
scan_y1 += tdy13;
scan_x2 += tdx12;
scan_y2 += tdy12;
}
curr_x2 = v2->x << SHIFT_CONST;
scan_x2 = v2->tx << SHIFT_CONST;
scan_y2 = v2->ty << SHIFT_CONST;
for (y = v2->y; y < v3->y; y++) {
textured_line(curr_x1 >> SHIFT_CONST, curr_x2 >> SHIFT_CONST, y,
scan_x1 >> SHIFT_CONST, scan_y1 >> SHIFT_CONST,
scan_x2 >> SHIFT_CONST, scan_y2 >> SHIFT_CONST, shifty, texture, buffer);
curr_x1 += dx13;
curr_x2 += dx23;
scan_x1 += tdx13;
scan_y1 += tdy13;
scan_x2 += tdx23;
scan_y2 += tdy23;
}
}