2 // This program is free software; you can redistribute it and/or
3 // modify it under the terms of the GNU General Public License as
4 // published by the Free Software Foundation; either version 2 of the
5 // License, or (at your option) any later version.
7 // This program is distributed in the hope that it will be useful, but
8 // WITHOUT ANY WARRANTY; without even the implied warranty of
9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
10 // General Public License for more details.
12 // You should have received a copy of the GNU General Public License
13 // along with this program; if not, write to the Free Software
14 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
16 #include "FGPNGTextureLoader.hxx"
25 GLuint FGPNGTextureLoader::loadTexture( const string & filename )
27 //header for testing if it is a png
31 FILE *fp = fopen(filename.c_str(), "rb");
37 fread(header, 1, 8, fp);
40 int is_png = !png_sig_cmp(header, 0, 8);
47 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
54 //create png info struct
55 png_infop info_ptr = png_create_info_struct(png_ptr);
57 png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
62 //create png info struct
63 png_infop end_info = png_create_info_struct(png_ptr);
65 png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
70 //png error stuff, not sure libpng man suggests this.
71 if (setjmp(png_jmpbuf(png_ptr))) {
72 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
78 png_init_io(png_ptr, fp);
80 //let libpng know you already read the first 8 bytes
81 png_set_sig_bytes(png_ptr, 8);
83 // read all the info up to the image data
84 png_read_info(png_ptr, info_ptr);
86 //variables to pass to get info
87 int bit_depth, color_type;
88 png_uint_32 twidth, theight;
91 png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
94 // Update the png info struct.
95 png_read_update_info(png_ptr, info_ptr);
98 int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
100 // Allocate the image_data as a big block, to be given to opengl
101 png_byte *image_data = new png_byte[rowbytes * theight];
103 //clean up memory and close stuff
104 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
109 //row_pointers is for pointing to image_data for reading the png with libpng
110 png_bytep *row_pointers = new png_bytep[theight];
112 //clean up memory and close stuff
113 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
118 // set the individual row_pointers to point at the correct offsets of image_data
119 for (png_uint_32 i = 0; i < theight; ++i)
120 row_pointers[theight - 1 - i] = image_data + i * rowbytes;
122 //read the png into image_data through row_pointers
123 png_read_image(png_ptr, row_pointers);
125 //Now generate the OpenGL texture object
127 glGenTextures(1, &texture);
128 glBindTexture(GL_TEXTURE_2D, texture);
129 gluBuild2DMipmaps( GL_TEXTURE_2D, 4, twidth, theight, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)image_data );
130 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
131 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR );
132 // glTexImage2D(GL_TEXTURE_2D,0, GL_RGBA, twidth, theight, 0,
133 // GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*) image_data);
134 // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
136 //clean up memory and close stuff
137 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
139 delete[] row_pointers;