pbGL

pbGL is a partial implementation of OpenGL 1.x for the Xbox using NXDK and PBKit. It's partially based on xgu-gl by JayFoxRox.

Status

Currently a subset of GL1.2 with some extensions from later versions is implemented.

To see what exactly is or isn't implemented, look at the GL headers.

Extension list:

• GL_ARB_multitexture (4 texture units available)
• GL_ARB_texture_env_combine
• GL_ARB_texture_env_add
• GL_EXT_paletted_texture (provides glColorTableEXT and GL_COLOR_INDEX8_EXT)
• GL_EXT_shared_texture_palette (provides GL_SHARED_TEXTURE_PALETTE_EXT)
• GL_PBGL_shared_texture_palette (provides GL_SHARED_TEXTURE_PALETTEn_PBGL and glActiveSharedPalettePBGL)
• GL_PBGL_texture_generate_mipmap (provides glGenerateMipmap, GL_EXPECT_MIPMAPS_PBGL and GL_GENERATE_MIPMAP)
• GL_PBGL_stats (provides GL_TEXTURE_MEMORY_USAGE_PBGL and GL_TEXTURE_COUNT_PBGL)

Known limitations:

• pbGL assumes that the color buffer is RGBA8888 and the depth buffer is D24S8;
• glVertexPointer etc do not make copies of the vertex data;
• GL_TEXTURE_1D, GL_TEXTURE_3D, GL_TEXTURE_CUBE_MAP are not supported yet;
• glTexImage2D etc only convert RGB888 <-> RGBA8888, otherwise you have to use the same format;
• GL lighting and material system is not fully implemented;
• maximum theoretical texture size is 4096x4096;
• NPOT textures are not supported and will likely explode;
• supported texture formats:
  • RGB888, RGBA8888
  • GL_COLOR_INDEX8_EXT (with either GL_RGB8 or GL_RGBA8 palettes, no format conversion)
  • ALPHA8, LUMINANCE8, LUMINANCE8_ALPHA8 (untested, no format conversion)
  • RGBA4444, RGB555, RGBA5551 (untested, no format conversion)

Usage

Link your project to libpbgl.lib and add the include folder to your include directories. If you are using the NXDK Makefile system, the easiest way to do this is something like this:

...
PBGL_DIR := path/to/pbgl

include $(NXDK_DIR)/Makefile
include $(PBGL_DIR)/config_pbgl.make
CFLAGS += $(PBGL_CFLAGS)
CXXFLAGS += $(PBGL_CFLAGS)

main.exe: $(PBGL_LIB)

You should then be able to use pbGL like any other GL implementation/loader, barring initialization and buffer swapping. Do keep in mind that you still have to set the display resolution before calling pbgl_init().

// define this to get GL function prototypes
#define GL_GLEXT_PROTOTYPES
#include <pbgl.h>
#include <GL/gl.h>
#include <GL/glext.h>
...
// argument indicates whether or not to init PBKit as well
pbgl_init(GL_TRUE);
// you're free to use GL functions after this
...
glClearColor(1.f, 0.f, 0.f, 1.f);
glClear(GL_COLOR_BUFFER_BIT);
// don't forget to swap buffers when you're done with the frame
pbgl_swap_buffers();
...
pbgl_shutdown(); // this will also shutdown PBKit

See the samples repository for more in-depth usage examples.

Credits

• NXDK authors and contributors for NXDK and the libraries included in it
• mborgerson for xsm64, which taught me a lot about PBKit
• xemu authors and abaire for figuring out how the GPU works
• dracc for XGU
• JayFoxRox for xgu-gl
• Ryzee120 for figuring out the Z bug
• XboxDev Discord server for help