org.lwjgl.opengl

Class EXTSeparateShaderObjects

java.lang.Object

org.lwjgl.opengl.EXTSeparateShaderObjects

public class EXTSeparateShaderObjects
extends java.lang.Object

Native bindings to the EXT_separate_shader_objects extension.

rior to this extension, GLSL requires multiple shader domains (vertex, fragment, geometry) to be linked into a single monolithic program object to specify a GLSL shader for each domain.

While GLSL's monolithic approach has some advantages for optimizing shaders as a unit that span multiple domains, all existing GPU hardware supports the more flexible mix-and-match approach.

HLSL9, Cg, the prior OpenGL assembly program extensions, and game console programmers favor a more flexible "mix-and-match" approach to specifying shaders independently for these different shader domains. Many developers build their shader content around the mix-and-match approach where they can use a single vertex shader with multiple fragment shaders (or vice versa).

This keep-it-simple extension adapts the "mix-and-match" shader domain model for GLSL so different GLSL program objects can be bound to different shader domains.

This extension redefines the operation of glUseProgram(GLenum program) to be equivalent to:

  glUseShaderProgramEXT(GL_VERTEX_SHADER, program);
 glUseShaderProgramEXT(GL_GEOMETRY_SHADER_EXT, program);
 glUseShaderProgramEXT(GL_FRAGMENT_SHADER, program);
 glActiveProgramEXT(program);

You can also call these commands separately to bind each respective domain. The GL_VERTEX_SHADER, GL_GEOMETRY_SHADER_EXT, and GL_FRAGMENT_SHADER tokens refer to the conventional vertex, geometry, and fragment domains respectively. glActiveProgramEXT specifies the program that glUniform* commands will update.

Separate linking creates the possibility that certain output varyings of a shader may go unread by the subsequent shader inputting varyings. In this case, the output varyings are simply ignored. It is also possible input varyings from a shader may not be written as output varyings of a preceding shader. In this case, the unwritten input varying values are undefined. Implementations are encouraged to zero these undefined input varying values.

This extension is a proof-of-concept that separate shader objects can work for GLSL and a response to repeated requests for this functionality. There are various loose ends, particularly when dealing with user-defined varyings. The hope is a future extension will improve this situation.

Requires OpenGL 2.0 or ARB_shader_objects.

Field Summary

Fields

Modifier and Type	Field and Description
static int	GL_ACTIVE_PROGRAM_EXT Accepted by type parameter to GetIntegerv and GetFloatv.

Method Summary

Modifier and Type	Method and Description
static void	glActiveProgramEXT(int program)
static int	glCreateShaderProgramEXT(int type, java.nio.ByteBuffer string)
static int	glCreateShaderProgramEXT(int type, java.lang.CharSequence string)
static void	glUseShaderProgramEXT(int type, int program)
static int	nglCreateShaderProgramEXT(int type, long string)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

GL_ACTIVE_PROGRAM_EXT

public static final int GL_ACTIVE_PROGRAM_EXT

Accepted by type parameter to GetIntegerv and GetFloatv.

See Also:

Constant Field Values

Method Detail

glUseShaderProgramEXT

public static void glUseShaderProgramEXT(int type,
                                         int program)

glActiveProgramEXT

public static void glActiveProgramEXT(int program)

nglCreateShaderProgramEXT

public static int nglCreateShaderProgramEXT(int type,
                                            long string)

glCreateShaderProgramEXT

public static int glCreateShaderProgramEXT(int type,
                                           java.nio.ByteBuffer string)

glCreateShaderProgramEXT

public static int glCreateShaderProgramEXT(int type,
                                           java.lang.CharSequence string)