littlecat@littlecat-HP-15-Notebook-PC:~/SRB2$ make -C src LINUX64=1 NOPNG=1
make: Entering directory `/home/littlecat/SRB2/src'
Linking lsdl2srb2...
../objs/Linux64/SDL/Release/m_misc.o: In function `M_PNGText':
/home/littlecat/SRB2/src/m_misc.c:715: undefined reference to `png_set_text'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_SavePNG':
/home/littlecat/SRB2/src/m_misc.c:1235: undefined reference to `png_create_write_struct'
/home/littlecat/SRB2/src/m_misc.c:1245: undefined reference to `png_create_info_struct'
/home/littlecat/SRB2/src/m_misc.c:1270: undefined reference to `png_init_io'
/home/littlecat/SRB2/src/m_misc.c:1273: undefined reference to `png_set_user_limits'
/home/littlecat/SRB2/src/m_misc.c:1278: undefined reference to `png_set_compression_level'
/home/littlecat/SRB2/src/m_misc.c:1279: undefined reference to `png_set_compression_mem_level'
/home/littlecat/SRB2/src/m_misc.c:1280: undefined reference to `png_set_compression_strategy'
/home/littlecat/SRB2/src/m_misc.c:1281: undefined reference to `png_set_compression_window_bits'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_PNGhdr':
/home/littlecat/SRB2/src/m_misc.c:616: undefined reference to `png_malloc'
/home/littlecat/SRB2/src/m_misc.c:625: undefined reference to `png_set_IHDR'
/home/littlecat/SRB2/src/m_misc.c:627: undefined reference to `png_write_info_before_PLTE'
/home/littlecat/SRB2/src/m_misc.c:628: undefined reference to `png_set_PLTE'
/home/littlecat/SRB2/src/m_misc.c:629: undefined reference to `png_free'
/home/littlecat/SRB2/src/m_misc.c:630: undefined reference to `png_set_filter'
/home/littlecat/SRB2/src/m_misc.c:631: undefined reference to `png_set_compression_strategy'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_SavePNG':
/home/littlecat/SRB2/src/m_misc.c:1287: undefined reference to `png_write_info'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_PNGImage':
/home/littlecat/SRB2/src/m_misc.c:722: undefined reference to `png_get_rowbytes'
/home/littlecat/SRB2/src/m_misc.c:723: undefined reference to `png_malloc'
/home/littlecat/SRB2/src/m_misc.c:730: undefined reference to `png_write_image'
/home/littlecat/SRB2/src/m_misc.c:731: undefined reference to `png_free'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_SavePNG':
/home/littlecat/SRB2/src/m_misc.c:1291: undefined reference to `png_write_end'
/home/littlecat/SRB2/src/m_misc.c:1292: undefined reference to `png_destroy_write_struct'
/home/littlecat/SRB2/src/m_misc.c:1262: undefined reference to `png_destroy_write_struct'
../objs/Linux64/SDL/Release/m_misc.o: In function `M_PNGhdr':
/home/littlecat/SRB2/src/m_misc.c:635: undefined reference to `png_set_IHDR'
/home/littlecat/SRB2/src/m_misc.c:637: undefined reference to `png_write_info_before_PLTE'
/home/littlecat/SRB2/src/m_misc.c:638: undefined reference to `png_set_compression_strategy'
collect2: error: ld returned 1 exit status
make: *** [../bin/Linux64/Release/lsdl2srb2] Error 1
make: Leaving directory `/home/littlecat/SRB2/src'