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
|
#include "texture.h"
#include "gfx/render_backend.h"
#include "error.h"
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#include <assert.h>
static void flip_horizontally(
unsigned char* pixels, int width, int height, int components) {
assert(pixels);
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width / 2; ++x) {
unsigned char* p1 = &pixels[(y * width + x) * components];
unsigned char* p2 = &pixels[(y * width + (width - x - 1)) * components];
for (int c = 0; c < components; ++c) {
unsigned char tmp = *p1;
*p1 = *p2;
*p2 = tmp;
p1++;
p2++;
}
}
}
}
// Note that the cubemap coordinate system uses the one in RenderMan:
//
// https://www.khronos.org/opengl/wiki/Cubemap_Texture
//
// This is what happens:
//
// - Cubemaps follow a left-handed coordinate system. Say, +X is right, +Y is
// up, and +Z is forward.
// - The texture coordinate system follow's DirectX's, so +V goes down, not up
// like it does in OpenGL.
//
// For this reason, we do X and Y flips when doing cubemap textures so that we
// can sample cubemaps as if they were given in the usual OpenGL coordinate
// system.
Texture* gfx_texture_load(
RenderBackend* render_backend, const LoadTextureCmd* cmd) {
assert(render_backend);
assert(cmd);
assert(cmd->origin == AssetFromFile || cmd->origin == AssetFromMemory);
assert(cmd->type == LoadTexture || cmd->type == LoadCubemap);
int width, height, components, old_components;
unsigned char* pixels[6] = {0};
switch (cmd->origin) {
case AssetFromFile:
switch (cmd->type) {
case LoadTexture: {
const char* filepath = mstring_cstr(&cmd->data.texture.filepath);
stbi_set_flip_vertically_on_load(0);
pixels[0] = stbi_load(filepath, &width, &height, &components, 0);
if (!pixels[0]) {
log_error("Failed to load texture file: %s", filepath);
}
break;
}
case LoadCubemap:
for (int i = 0; i < 6; ++i) {
// Flip +Y and -Y textures vertically.
stbi_set_flip_vertically_on_load(((i == 2) || (i == 3)) ? 1 : 0);
const char* filepath =
mstring_cstr(&cmd->data.cubemap.filepaths.filepath_pos_x + i);
stbi_uc* image_pixels =
stbi_load(filepath, &width, &height, &components, 0);
if (!image_pixels) {
log_error("Failed to load texture file: %s", filepath);
break;
}
if (i > 0 && components != old_components) {
log_error("All textures in a cubemap must have the same number of "
"components");
break;
}
if ((i != 2) && (i != 3)) {
flip_horizontally(image_pixels, width, height, components);
}
pixels[i] = image_pixels;
old_components = components;
}
break;
}
break;
case AssetFromMemory:
// TODO: Load textures from memory.
log_error("Loading textures from memory is not yet implemented");
return 0;
}
// Error out if we failed to load a texture.
if (!pixels[0] ||
(cmd->type == LoadCubemap &&
(!pixels[1] || !pixels[2] || !pixels[3] || !pixels[4] || !pixels[5]))) {
for (int i = 0; i < 6; ++i) {
if (pixels[i]) {
stbi_image_free(pixels[i]);
}
}
return 0;
}
TextureDesc desc = (TextureDesc){0};
desc.width = width;
desc.height = height;
switch (cmd->type) {
case LoadTexture:
desc.dimension = Texture2D;
break;
case LoadCubemap:
desc.dimension = TextureCubeMap;
break;
}
switch (components) {
case 3:
switch (cmd->colour_space) {
case LinearColourSpace:
desc.format = TextureRGB8;
break;
case sRGB:
desc.format = TextureSRGB8;
break;
default:
log_error("Unsupported texture colour space: %d", cmd->colour_space);
return 0;
}
break;
case 4:
switch (cmd->colour_space) {
case LinearColourSpace:
desc.format = TextureRGBA8;
break;
case sRGB:
desc.format = TextureSRGBA8;
break;
default:
log_error("Unsupported texture colour space: %d", cmd->colour_space);
return 0;
}
break;
default:
log_error("Unsupported number of texture components: %d", components);
return 0;
}
desc.filtering = cmd->filtering;
desc.mipmaps = cmd->mipmaps;
switch (cmd->type) {
case LoadTexture:
desc.data.pixels = pixels[0];
break;
case LoadCubemap:
for (int i = 0; i < 6; ++i) {
*(&desc.data.cubemap.pixels_pos_x + i) = pixels[i];
}
break;
}
Texture* texture = gfx_make_texture(render_backend, &desc);
for (int i = 0; i < 6; ++i) {
if (pixels[i]) {
stbi_image_free(pixels[i]);
}
}
return texture;
}
|
