1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
|
#include <stdio.h>
#include <stdlib.h>
#include "plat.h"
#include "str.h"
#include "vid_enums.h"
typedef struct {
float r, g, b;
} vec3;
typedef struct {
unsigned char r, g, b, a;
} Colour;
typedef struct {
Colour* pixels;
int w, h;
} Image;
typedef struct {
vec3 start, end;
unsigned char indices[4 * 4];
} Block;
const char* format_names[] = {
#define x(n) #n,
texture_format_xmacro()
#undef x
};
unsigned encode_endpoint(const vec3* v) {
return
((unsigned)(v->r * 31.9999f) << 11) |
((unsigned)(v->g * 63.9999f) << 5) |
((unsigned)(v->b * 31.9999f));
}
void get_block(Block* block, Colour* pixels, int stride) {
int x, y, i;
vec3 cols[4 * 4];
vec3 palette[3];
vec3 s, e;
unsigned es, ee;
float cd;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
Colour pixel = pixels[x + y * stride];
vec3 vec;
vec.r = (float)pixel.r / 255.0f;
vec.g = (float)pixel.g / 255.0f;
vec.b = (float)pixel.b / 255.0f;
cols[x + y * 4] = vec;
}
}
cd = -1.0f;
for (i = 0; i < 4 * 4; i++) {
int j;
vec3* a = &cols[i];
for (j = i + 1; j < 4 * 4; j++) {
vec3* b = &cols[j];
float d =
(b->r - a->r) * (b->r - a->r) +
(b->g - a->g) * (b->g - a->g) +
(b->b - a->b) * (b->b - a->b);
if (d > cd) {
cd = d;
s = *a;
e = *b;
}
}
}
es = encode_endpoint(&s);
ee = encode_endpoint(&e);
if (es == ee) {
block->start = s;
block->end.r = 0.0f;
block->end.g = 0.0f;
block->end.b = 0.0f;
for (i = 0; i < 16; i++) {
block->indices[i] = 0;
}
return;
}
if (es < ee) {
/* todo alpha */
vec3 t = s;
s = e;
e = t;
}
palette[0] = s;
palette[1] = e;
palette[2].r = 0.666666f*palette[0].r + 0.333333f*palette[1].r;
palette[2].g = 0.666666f*palette[0].g + 0.333333f*palette[1].g;
palette[2].b = 0.666666f*palette[0].b + 0.333333f*palette[1].b;
palette[3].r = 0.333333f*palette[0].r + 0.666666f*palette[1].r;
palette[3].g = 0.333333f*palette[0].g + 0.666666f*palette[1].g;
palette[3].b = 0.333333f*palette[0].b + 0.666666f*palette[1].b;
for (i = 0; i < 4 * 4; i++) {
vec3* col = &cols[i];
int closest = 0, j;
float cd = 99999.0f;
for (j = 0; j < 4; j++) {
vec3* p = &palette[j];
float d =
(p->r - col->r) * (p->r - col->r) +
(p->g - col->g) * (p->g - col->g) +
(p->b - col->b) * (p->b - col->b);
if (d < cd) {
cd = d;
closest = j;
}
}
block->indices[i] = closest;
}
block->start = s;
block->end = e;
}
void compress_block(const Block* block, FILE* f) {
int i;
unsigned start = encode_endpoint(&block->start);
unsigned end = encode_endpoint(&block->end);
unsigned indices = 0;
fwrite(&start, 1, 2, f);
fwrite(&end, 1, 2, f);
for (i = 0; i < 4 * 4; i++) {
int idx = (4 * 4 - 1) - i;
idx = i;
indices |= block->indices[i] << (idx * 2);
}
fwrite(&indices, 1, 4, f);
}
void compress_bc1(Colour* pixels, int w, int h, FILE* f) {
int x, y, cw, ch;
Block block;
cw = w / 4;
ch = h / 4;
for (y = 0; y < ch; y++) {
for (x = 0; x < cw; x++) {
get_block(&block, &pixels[x * 4 + y * 4 * w], w);
compress_block(&block, f);
}
}
}
void convert(Image* image, Texture_Format target, FILE* f) {
fwrite("TXTR", 1, 4, f);
fwrite(&image->w, 1, 4, f);
fwrite(&image->h, 1, 4, f);
fwrite(&target, 1, 4, f);
switch (target) {
case texture_format_bc1:
compress_bc1(image->pixels, image->w, image->h, f);
break;
default:
print_err("Unsupported target format.\n");
pbreak(40);
}
}
Texture_Format texture_format_from_string(const char* s) {
int i, e = sizeof format_names / sizeof *format_names;
for (i = 0; i < e; i++)
if (string_equal(s, format_names[i]))
return (Texture_Format)i;
print_err("Invalid texture format %s\n", s);
pbreak(10);
return (Texture_Format)0;
}
int main(int argc, const char** argv) {
FILE* outfile, * infile;
char bmp_magic[2];
unsigned bmp_offset;
int bmp_w, bmp_h, s, x, y;
unsigned short bmp_bits;
Colour* buffer;
Image img;
Colour pixel;
Texture_Format target;
if (argc < 4) {
print_err("Usage: %s infile outfile format.\n", argv[0]);
return 1;
}
infile = fopen(argv[1], "rb");
if (!infile) {
print_err("Failed to open %s.\n", argv[1]);
return 2;
}
target = texture_format_from_string(argv[3]);
fread(bmp_magic, 2, 1, infile);
if (bmp_magic[0] != 'B' || bmp_magic[1] != 'M') {
print_err("Not a valid bitmap file.\n");
return 3;
}
fseek(infile, 10, SEEK_SET);
fread(&bmp_offset, 4, 1, infile);
fseek(infile, 18, SEEK_SET);
fread(&bmp_w, 4, 1, infile);
fread(&bmp_h, 4, 1, infile);
fseek(infile, 28, SEEK_SET);
fread(&bmp_bits, 2, 1, infile);
if (bmp_bits != 32) {
print_err("Bitmap must have 32 bit pixels. Instead has %d bit pixels.\n", bmp_bits);
return 4;
}
if (bmp_w % 4 != 0 || bmp_h % 4 != 0) {
print_err("Bitmap must have a size divisible by four.\n");
return 5;
}
fseek(infile, bmp_offset, SEEK_SET);
s = bmp_w * bmp_h;
buffer = malloc(s * 4);
/* Flip & read. */
for (y = 0; y < bmp_h; y++) {
for (x = 0; x < bmp_w; x++) {
unsigned char t;
fread(&pixel, 1, 4, infile);
t = pixel.r;
pixel.r = pixel.b;
pixel.b = t;
if (pixel.a == 0) {
pixel.r = 0;
pixel.g = 0;
pixel.b = 0;
}
buffer[x + (bmp_h - y - 1) * bmp_w] = pixel;
}
}
outfile = fopen(argv[2], "wb");
if (!outfile) {
print_err("Failed to open %s.\n", argv[2]);
return 6;
}
img.pixels = buffer;
img.w = bmp_w;
img.h = bmp_h;
convert(&img, target, outfile);
fclose(outfile);
return 0;
}
|