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.
23 #include "FGPNGTextureLoader.hxx"
26 #include <GLUT/glut.h>
36 GLuint FGPNGTextureLoader::loadTexture( const string & filename )
38 //header for testing if it is a png
42 FILE *fp = fopen(filename.c_str(), "rb");
48 fread(header, 1, 8, fp);
51 int is_png = !png_sig_cmp(header, 0, 8);
58 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
65 //create png info struct
66 png_infop info_ptr = png_create_info_struct(png_ptr);
68 png_destroy_read_struct(&png_ptr, (png_infopp) NULL, (png_infopp) NULL);
73 //create png info struct
74 png_infop end_info = png_create_info_struct(png_ptr);
76 png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
81 //png error stuff, not sure libpng man suggests this.
82 if (setjmp(png_jmpbuf(png_ptr))) {
83 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
89 png_init_io(png_ptr, fp);
91 //let libpng know you already read the first 8 bytes
92 png_set_sig_bytes(png_ptr, 8);
94 // read all the info up to the image data
95 png_read_info(png_ptr, info_ptr);
97 //variables to pass to get info
98 int bit_depth, color_type;
99 png_uint_32 twidth, theight;
101 // get info about png
102 png_get_IHDR(png_ptr, info_ptr, &twidth, &theight, &bit_depth, &color_type,
105 // Update the png info struct.
106 png_read_update_info(png_ptr, info_ptr);
108 // Row size in bytes.
109 int rowbytes = png_get_rowbytes(png_ptr, info_ptr);
111 // Allocate the image_data as a big block, to be given to opengl
112 png_byte *image_data = new png_byte[rowbytes * theight];
114 //clean up memory and close stuff
115 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
120 //row_pointers is for pointing to image_data for reading the png with libpng
121 png_bytep *row_pointers = new png_bytep[theight];
123 //clean up memory and close stuff
124 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
129 // set the individual row_pointers to point at the correct offsets of image_data
130 for (png_uint_32 i = 0; i < theight; ++i)
131 row_pointers[theight - 1 - i] = image_data + i * rowbytes;
133 //read the png into image_data through row_pointers
134 png_read_image(png_ptr, row_pointers);
136 //Now generate the OpenGL texture object
138 glGenTextures(1, &texture);
139 glBindTexture(GL_TEXTURE_2D, texture);
140 gluBuild2DMipmaps( GL_TEXTURE_2D, 4, twidth, theight, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)image_data );
141 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR );
142 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR );
143 // glTexImage2D(GL_TEXTURE_2D,0, GL_RGBA, twidth, theight, 0,
144 // GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*) image_data);
145 // glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
147 //clean up memory and close stuff
148 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
150 delete[] row_pointers;