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texture.cpp
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texture.cpp
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#include <iostream>
#include <vector>
#include <cstdint>
#include <cassert>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#include "draw.h"
#include "texture.h"
Texture::Texture(const std::string filename) : img_w(0), img_h(0), count(0), size(0), img() {
int nchannels = -1, w, h;
unsigned char* pixmap = stbi_load(filename.c_str(), &w, &h, &nchannels, 0);
if (!pixmap) {
std::cerr << "Error: can not load the textures" << std::endl;
return;
}
if (4 != nchannels) {
std::cerr << "Error: the texture must be a 32 bit image" << std::endl;
stbi_image_free(pixmap);
return;
}
if (w != h * int(w / h)) {
std::cerr << "Error: the texture file must contain N square textures packed horizontally" << std::endl;
stbi_image_free(pixmap);
return;
}
count = w / h;
size = w / count;
img_w = w;
img_h = h;
img = std::vector<uint32_t>(w * h);
for (int j = 0; j < h; j++) {
for (int i = 0; i < w; i++) {
uint8_t r = pixmap[(i + j * w) * 4 + 0];
uint8_t g = pixmap[(i + j * w) * 4 + 1];
uint8_t b = pixmap[(i + j * w) * 4 + 2];
uint8_t a = pixmap[(i + j * w) * 4 + 3];
img[i + j * w] = pack_color(r, g, b, a);
}
}
stbi_image_free(pixmap);
}
uint32_t& Texture::get(const size_t i, const size_t j, const size_t idx) {
assert(i < size && j < size && idx < count);
return img[i + idx * size + j * img_w];
}
std::vector<uint32_t> Texture::get_scaled_column(const size_t texture_id, const size_t tex_coord, const size_t column_height) {
assert(tex_coord < size && texture_id < count);
std::vector<uint32_t> column(column_height);
for (size_t y = 0; y < column_height; y++) {
column[y] = get(tex_coord, (y * size) / column_height, texture_id);
}
return column;
}