public class NVShaderBufferLoad
extends java.lang.Object
At a very coarse level, GL has evolved in a way that allows applications to replace many of the original state machine variables with blocks of user-defined data. For example, the current vertex state has been augmented by vertex buffer objects, fixed-function shading state and parameters have been replaced by shaders/programs and constant buffers, etc. Applications switch between coarse sets of state by binding objects to the context or to other container objects (e.g. vertex array objects) instead of manipulating state variables of the context. In terms of the number of GL commands required to draw an object, modern applications are orders of magnitude more efficient than legacy applications, but this explosion of objects bound to other objects has led to a new bottleneck - pointer chasing and CPU L2 cache misses in the driver, and general L2 cache pollution.
This extension provides a mechanism to read from a flat, 64-bit GPU address space from programs/shaders, to query GPU addresses of buffer objects at the API level, and to bind buffer objects to the context in such a way that they can be accessed via their GPU addresses in any shader stage.
The intent is that applications can avoid re-binding buffer objects or updating constants between each Draw call and instead simply use a VertexAttrib (or TexCoord, or InstanceID, or...) to "point" to the new object's state. In this way, one of the cheapest "state" updates (from the CPU's point of view) can be used to effect a significant state change in the shader similarly to how a pointer change may on the CPU. At the same time, this relieves the limits on how many buffer objects can be accessed at once by shaders, and allows these buffer object accesses to be exposed as C-style pointer dereferences in the shading language.
As a very simple example, imagine packing a group of similar objects' constants into a single buffer object and pointing your program at object
<i> by setting glVertexAttribI1iEXT(attrLoc, i); and using a shader as such:
struct MyObjectType {
mat4x4 modelView;
vec4 materialPropertyX;
// etc.
};
uniform MyObjectType *allObjects;
in int objectID; // bound to attrLoc
...
mat4x4 thisObjectsMatrix = allObjects[objectID].modelView;
// do transform, shading, etc.This is beneficial in much the same way that texture arrays allow choosing between similar, but independent, texture maps with a single coordinate identifying which slice of the texture to use. It also resembles instancing, where a lightweight change (incrementing the instance ID) can be used to generate a different and interesting result, but with additional flexibility over instancing because the values are app-controlled and not a single incrementing counter.
Dependent pointer fetches are allowed, so more complex scene graph structures can be built into buffer objects providing significant new flexibility in the use of shaders. Another simple example, showing something you can't do with existing functionality, is to do dependent fetches into many buffer objects:
GenBuffers(N, dataBuffers);
GenBuffers(1, &pointerBuffer);
GLuint64EXT gpuAddrs[N];
for (i = 0; i < N; ++i) {
BindBuffer(target, dataBuffers[i]);
BufferData(target, size[i], myData[i], STATIC_DRAW);
// get the address of this buffer and make it resident.
GetBufferParameterui64vNV(target, BUFFER_GPU_ADDRESS,
gpuaddrs[i]);
MakeBufferResidentNV(target, READ_ONLY);
}
GLuint64EXT pointerBufferAddr;
BindBuffer(target, pointerBuffer);
BufferData(target, sizeof(GLuint64EXT)*N, gpuAddrs, STATIC_DRAW);
GetBufferParameterui64vNV(target, BUFFER_GPU_ADDRESS,
&pointerBufferAddr);
MakeBufferResidentNV(target, READ_ONLY);
// now in the shader, we can use a double indirection
vec4 **ptrToBuffers = pointerBufferAddr;
vec4 *ptrToBufferI = ptrToBuffers[i];This allows simultaneous access to more buffers than EXT_bindable_uniform (MAX_VERTEX_BINDABLE_UNIFORMS_EXT, etc.) and each can be larger than
MAX_BINDABLE_UNIFORM_SIZE_EXT.
| Modifier and Type | Field and Description |
|---|---|
static int |
GL_BUFFER_GPU_ADDRESS_NV
Accepted by the
pname parameter of GetBufferParameterui64vNV, GetNamedBufferParameterui64vNV. |
static int |
GL_GPU_ADDRESS_NV
Returned by the
type parameter of GetActiveUniform. |
static int |
GL_MAX_SHADER_BUFFER_ADDRESS_NV
Accepted by the
value parameter of GetIntegerui64vNV. |
| Modifier and Type | Method and Description |
|---|---|
static long |
glGetBufferParameterui64NV(int target,
int pname) |
static void |
glGetBufferParameterui64vNV(int target,
int pname,
long[] params)
Array version of:
GetBufferParameterui64vNV |
static void |
glGetBufferParameterui64vNV(int target,
int pname,
java.nio.LongBuffer params) |
static long |
glGetIntegerui64NV(int value) |
static void |
glGetIntegerui64vNV(int value,
long[] result)
Array version of:
GetIntegerui64vNV |
static void |
glGetIntegerui64vNV(int value,
java.nio.LongBuffer result) |
static long |
glGetNamedBufferParameterui64NV(int buffer,
int pname) |
static void |
glGetNamedBufferParameterui64vNV(int buffer,
int pname,
long[] params)
Array version of:
GetNamedBufferParameterui64vNV |
static void |
glGetNamedBufferParameterui64vNV(int buffer,
int pname,
java.nio.LongBuffer params) |
static long |
glGetUniformui64NV(int program,
int location) |
static void |
glGetUniformui64vNV(int program,
int location,
long[] params)
Array version of:
GetUniformui64vNV |
static void |
glGetUniformui64vNV(int program,
int location,
java.nio.LongBuffer params) |
static boolean |
glIsBufferResidentNV(int target) |
static boolean |
glIsNamedBufferResidentNV(int buffer) |
static void |
glMakeBufferNonResidentNV(int target) |
static void |
glMakeBufferResidentNV(int target,
int access) |
static void |
glMakeNamedBufferNonResidentNV(int buffer) |
static void |
glMakeNamedBufferResidentNV(int buffer,
int access) |
static void |
glProgramUniformui64NV(int program,
int location,
long value) |
static void |
glProgramUniformui64vNV(int program,
int location,
long[] value)
Array version of:
ProgramUniformui64vNV |
static void |
glProgramUniformui64vNV(int program,
int location,
java.nio.LongBuffer value) |
static void |
glUniformui64NV(int location,
long value) |
static void |
glUniformui64vNV(int location,
long[] value)
Array version of:
Uniformui64vNV |
static void |
glUniformui64vNV(int location,
java.nio.LongBuffer value) |
static void |
nglGetBufferParameterui64vNV(int target,
int pname,
long params) |
static void |
nglGetIntegerui64vNV(int value,
long result) |
static void |
nglGetNamedBufferParameterui64vNV(int buffer,
int pname,
long params) |
static void |
nglGetUniformui64vNV(int program,
int location,
long params) |
static void |
nglProgramUniformui64vNV(int program,
int location,
int count,
long value) |
static void |
nglUniformui64vNV(int location,
int count,
long value) |
public static final int GL_BUFFER_GPU_ADDRESS_NV
pname parameter of GetBufferParameterui64vNV, GetNamedBufferParameterui64vNV.public static final int GL_GPU_ADDRESS_NV
type parameter of GetActiveUniform.public static final int GL_MAX_SHADER_BUFFER_ADDRESS_NV
value parameter of GetIntegerui64vNV.public static void glMakeBufferResidentNV(int target,
int access)
public static void glMakeBufferNonResidentNV(int target)
public static boolean glIsBufferResidentNV(int target)
public static void glMakeNamedBufferResidentNV(int buffer,
int access)
public static void glMakeNamedBufferNonResidentNV(int buffer)
public static boolean glIsNamedBufferResidentNV(int buffer)
public static void nglGetBufferParameterui64vNV(int target,
int pname,
long params)
public static void glGetBufferParameterui64vNV(int target,
int pname,
java.nio.LongBuffer params)
public static long glGetBufferParameterui64NV(int target,
int pname)
public static void nglGetNamedBufferParameterui64vNV(int buffer,
int pname,
long params)
public static void glGetNamedBufferParameterui64vNV(int buffer,
int pname,
java.nio.LongBuffer params)
public static long glGetNamedBufferParameterui64NV(int buffer,
int pname)
public static void nglGetIntegerui64vNV(int value,
long result)
public static void glGetIntegerui64vNV(int value,
java.nio.LongBuffer result)
public static long glGetIntegerui64NV(int value)
public static void glUniformui64NV(int location,
long value)
public static void nglUniformui64vNV(int location,
int count,
long value)
public static void glUniformui64vNV(int location,
java.nio.LongBuffer value)
public static void nglGetUniformui64vNV(int program,
int location,
long params)
public static void glGetUniformui64vNV(int program,
int location,
java.nio.LongBuffer params)
public static long glGetUniformui64NV(int program,
int location)
public static void glProgramUniformui64NV(int program,
int location,
long value)
public static void nglProgramUniformui64vNV(int program,
int location,
int count,
long value)
public static void glProgramUniformui64vNV(int program,
int location,
java.nio.LongBuffer value)
public static void glGetBufferParameterui64vNV(int target,
int pname,
long[] params)
GetBufferParameterui64vNVpublic static void glGetNamedBufferParameterui64vNV(int buffer,
int pname,
long[] params)
GetNamedBufferParameterui64vNVpublic static void glGetIntegerui64vNV(int value,
long[] result)
GetIntegerui64vNVpublic static void glUniformui64vNV(int location,
long[] value)
Uniformui64vNVpublic static void glGetUniformui64vNV(int program,
int location,
long[] params)
GetUniformui64vNVpublic static void glProgramUniformui64vNV(int program,
int location,
long[] value)
ProgramUniformui64vNVCopyright LWJGL. All Rights Reserved. License terms.