161 lines
5 KiB
C++
161 lines
5 KiB
C++
#include "image_texture.hpp"
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#include <png.h>
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#include <cmath>
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namespace endofthejedi {
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bool ImageTexture::loadPng()
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{
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m_valid = false;
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//header for testing if it is a png
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png_byte header[8];
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//open file as binary
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FILE *fp = fopen(m_path.c_str(), "rb");
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if (!fp) {
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printf("[image_texture] warning: could not open png file to load: %s\n", m_path.c_str());
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return false;
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}
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//read the header
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fread(header, 1, 8, fp);
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//test if png
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int is_png = !png_sig_cmp(header, 0, 8);
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if (!is_png) {
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puts("warning: image loader: file is not PNG!");
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fclose(fp);
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return false;
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}
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//create png struct
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png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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if (!png_ptr) {
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fclose(fp);
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return false;
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}
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//create png info struct
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png_infop info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr) {
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png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
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fclose(fp);
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return false;
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}
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//create png info struct
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png_infop end_info = png_create_info_struct(png_ptr);
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if (!end_info) {
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png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
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fclose(fp);
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return false;
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}
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//png error stuff, not sure libpng man suggests this.
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if (setjmp(png_jmpbuf(png_ptr))) {
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png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
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fclose(fp);
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return false;
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}
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//init png reading
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png_init_io(png_ptr, fp);
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//let libpng know you already read the first 8 bytes
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png_set_sig_bytes(png_ptr, 8);
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// read all the info up to the image data
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png_read_info(png_ptr, info_ptr);
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//variables to pass to get info
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int bit_depth, color_type;
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png_uint_32 twidth, theight;
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// get info about png
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png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
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NULL, NULL, NULL);
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//update width and height based on png info
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m_width = twidth;
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m_height = theight;
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int pot_width = (int) pow(2, ceilf(log2f(m_width)));
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int pot_height = (int) pow(2, ceilf(log2f(m_height)));
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m_uv_scale_x = m_width / (float) pot_width;
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m_uv_scale_y = m_height / (float) pot_height;
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/*puts("#########################################");*/
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/*printf("# PNG: width=%d, height=%d\n", width, height);*/
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/*printf("# powers of two: w=%d, h=%d\n", pot_width, pot_height);*/
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/*puts("#########################################");*/
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// Update the png info struct.
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png_read_update_info(png_ptr, info_ptr);
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// Row size in bytes.
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int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
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int pot_rowbytes = 4 * (int) pow(2, ceilf(log2f(rowbytes/4)));
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/*printf("rowbytes: %d, pot_rowbytes=%d\n", rowbytes, pot_rowbytes);*/
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// Allocate the image_data as a big block, to be given to opengl
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png_byte *image_data = (png_byte *) calloc(pot_rowbytes * pot_height, sizeof(png_byte));
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if (!image_data) {
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//clean up memory and close stuff
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png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
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fclose(fp);
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return false;
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}
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//row_pointers is for pointing to image_data for reading the png with libpng
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png_bytep *row_pointers = (png_bytep *) malloc(sizeof(png_bytep) * m_height);
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if (!row_pointers) {
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//clean up memory and close stuff
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png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
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free(image_data);
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fclose(fp);
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return false;
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}
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// set the individual row_pointers to point at the correct offsets of image_data
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for (int i = 0; i < m_height; ++i) {
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row_pointers[m_height - 1 - i] = image_data + i * pot_rowbytes;
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}
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//read the png into image_data through row_pointers
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png_read_image(png_ptr, row_pointers);
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//Now generate the OpenGL texture object
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glGenTextures(1, &m_texture_id);
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glBindTexture(GL_TEXTURE_2D, m_texture_id);
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glTexImage2D(GL_TEXTURE_2D,
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0,
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GL_RGBA,
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pot_width,
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pot_height,
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0,
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GL_RGBA,
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GL_UNSIGNED_BYTE,
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(GLvoid*) image_data);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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// TODO: make selectable via switch!
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
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//clean up memory and close stuff
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png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
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free(image_data);
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free(row_pointers);
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fclose(fp);
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m_valid = true;
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return true;
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}
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}
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