Class ARBShaderImageLoadStore
- java.lang.Object
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- org.lwjgl.opengl.ARBShaderImageLoadStore
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public class ARBShaderImageLoadStore extends java.lang.Object
Native bindings to the ARB_shader_image_load_store extension.This extension provides GLSL built-in functions allowing shaders to load from, store to, and perform atomic read-modify-write operations to a single level of a texture object from any shader stage. These built-in functions are named imageLoad(), imageStore(), and imageAtomic*(), respectively, and accept integer texel coordinates to identify the texel accessed. The extension adds the notion of "image units" to the OpenGL API, to which texture levels are bound for access by the GLSL built-in functions. To allow shaders to specify the image unit to access, GLSL provides a new set of data types ("image*") similar to samplers. Each image variable is assigned an integer value to identify an image unit to access, which is specified using Uniform*() APIs in a manner similar to samplers.
This extension also provides the capability to explicitly enable "early" per-fragment tests, where operations like depth and stencil testing are performed prior to fragment shader execution. In unextended OpenGL, fragment shaders never have any side effects and implementations can sometimes perform per-fragment tests and discard some fragments prior to executing the fragment shader. Since this extension allows fragment shaders to write to texture and buffer object memory using the built-in image functions, such optimizations could lead to non-deterministic results. To avoid this, implementations supporting this extension may not perform such optimizations on shaders having such side effects. However, enabling early per-fragment tests guarantees that such tests will be performed prior to fragment shader execution, and ensures that image stores and atomics will not be performed by fragment shader invocations where these per-fragment tests fail.
Finally, this extension provides both a GLSL built-in function and an OpenGL API function allowing applications some control over the ordering of image loads, stores, and atomics relative to other OpenGL pipeline operations accessing the same memory. Because the extension provides the ability to perform random accesses to texture or buffer object memory, such accesses are not easily tracked by the OpenGL driver. To avoid the need for heavy-handed synchronization at the driver level, this extension requires manual synchronization. The MemoryBarrier() OpenGL API function allows applications to specify a bitfield indicating the set of OpenGL API operations to synchronize relative to shader memory access. The memoryBarrier() GLSL built-in function provides a synchronization point within a given shader invocation to ensure that all memory accesses performed prior to the synchronization point complete prior to any started after the synchronization point.
Requires
OpenGL 3.0
and GLSL 1.30. Promoted to core inOpenGL 4.2
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Field Summary
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method and Description static void
glBindImageTexture(int unit, int texture, int level, boolean layered, int layer, int access, int format)
Binds a level of a texture to an image unit.static void
glMemoryBarrier(int barriers)
Defines a barrier ordering memory transactions.
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Field Detail
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GL_MAX_IMAGE_UNITS, GL_MAX_COMBINED_IMAGE_UNITS_AND_FRAGMENT_OUTPUTS, GL_MAX_IMAGE_SAMPLES, GL_MAX_VERTEX_IMAGE_UNIFORMS, GL_MAX_TESS_CONTROL_IMAGE_UNIFORMS, GL_MAX_TESS_EVALUATION_IMAGE_UNIFORMS, GL_MAX_GEOMETRY_IMAGE_UNIFORMS, GL_MAX_FRAGMENT_IMAGE_UNIFORMS, GL_MAX_COMBINED_IMAGE_UNIFORMS
Accepted by thepname
parameter of GetBooleanv, GetIntegerv, GetFloatv, GetDoublev, and GetInteger64v.
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GL_IMAGE_BINDING_NAME, GL_IMAGE_BINDING_LEVEL, GL_IMAGE_BINDING_LAYERED, GL_IMAGE_BINDING_LAYER, GL_IMAGE_BINDING_ACCESS, GL_IMAGE_BINDING_FORMAT
Accepted by thetarget
parameter of GetIntegeri_v and GetBooleani_v.
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GL_VERTEX_ATTRIB_ARRAY_BARRIER_BIT, GL_ELEMENT_ARRAY_BARRIER_BIT, GL_UNIFORM_BARRIER_BIT, GL_TEXTURE_FETCH_BARRIER_BIT, GL_SHADER_IMAGE_ACCESS_BARRIER_BIT, GL_COMMAND_BARRIER_BIT, GL_PIXEL_BUFFER_BARRIER_BIT, GL_TEXTURE_UPDATE_BARRIER_BIT, GL_BUFFER_UPDATE_BARRIER_BIT, GL_FRAMEBUFFER_BARRIER_BIT, GL_TRANSFORM_FEEDBACK_BARRIER_BIT, GL_ATOMIC_COUNTER_BARRIER_BIT, GL_ALL_BARRIER_BITS
Accepted by thebarriers
parameter of MemoryBarrier.
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GL_IMAGE_1D, GL_IMAGE_2D, GL_IMAGE_3D, GL_IMAGE_2D_RECT, GL_IMAGE_CUBE, GL_IMAGE_BUFFER, GL_IMAGE_1D_ARRAY, GL_IMAGE_2D_ARRAY, GL_IMAGE_CUBE_MAP_ARRAY, GL_IMAGE_2D_MULTISAMPLE, GL_IMAGE_2D_MULTISAMPLE_ARRAY, GL_INT_IMAGE_1D, GL_INT_IMAGE_2D, GL_INT_IMAGE_3D, GL_INT_IMAGE_2D_RECT, GL_INT_IMAGE_CUBE, GL_INT_IMAGE_BUFFER, GL_INT_IMAGE_1D_ARRAY, GL_INT_IMAGE_2D_ARRAY, GL_INT_IMAGE_CUBE_MAP_ARRAY, GL_INT_IMAGE_2D_MULTISAMPLE, GL_INT_IMAGE_2D_MULTISAMPLE_ARRAY, GL_UNSIGNED_INT_IMAGE_1D, GL_UNSIGNED_INT_IMAGE_2D, GL_UNSIGNED_INT_IMAGE_3D, GL_UNSIGNED_INT_IMAGE_2D_RECT, GL_UNSIGNED_INT_IMAGE_CUBE, GL_UNSIGNED_INT_IMAGE_BUFFER, GL_UNSIGNED_INT_IMAGE_1D_ARRAY, GL_UNSIGNED_INT_IMAGE_2D_ARRAY, GL_UNSIGNED_INT_IMAGE_CUBE_MAP_ARRAY, GL_UNSIGNED_INT_IMAGE_2D_MULTISAMPLE, GL_UNSIGNED_INT_IMAGE_2D_MULTISAMPLE_ARRAY
Returned by thetype
parameter of GetActiveUniform.
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GL_IMAGE_FORMAT_COMPATIBILITY_TYPE
Accepted by thevalue
parameter of GetTexParameteriv, GetTexParameterfv, GetTexParameterIiv, and GetTexParameterIuiv.
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GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE, GL_IMAGE_FORMAT_COMPATIBILITY_BY_CLASS
Returned in thedata
parameter of GetTexParameteriv, GetTexParameterfv, GetTexParameterIiv, and GetTexParameterIuiv whenvalue
is IMAGE_FORMAT_COMPATIBILITY_TYPE.
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Method Detail
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glBindImageTexture
public static void glBindImageTexture(int unit, int texture, int level, boolean layered, int layer, int access, int format)
Binds a level of a texture to an image unit.- Parameters:
unit
- the index of the image unit to which to bind the texturetexture
- the name of the texture to bind to the image unitlevel
- the level of the texture that is to be boundlayered
- whether a layered texture binding is to be establishedlayer
- iflayered
is false, specifies the layer of texture to be bound to the image unit. Ignored otherwise.access
- a token indicating the type of access that will be performed on the imageformat
- the format that the elements of the image will be treated as for the purposes of formatted stores
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glMemoryBarrier
public static void glMemoryBarrier(int barriers)
Defines a barrier ordering memory transactions.- Parameters:
barriers
- the barriers to insert (bitwise combination). One or more of:
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