Package org.lwjgl.opengl

Class ARBDrawIndirect

java.lang.Object

org.lwjgl.opengl.ARBDrawIndirect

public class ARBDrawIndirect
extends java.lang.Object

Native bindings to the ARB_draw_indirect extension.

This extension provides a mechanism for supplying the arguments to a DrawArraysInstanced or DrawElementsInstancedBaseVertex from buffer object memory. This is not particularly useful for applications where the CPU knows the values of the arguments beforehand, but is helpful when the values will be generated on the GPU through any mechanism that can write to a buffer object including image stores, atomic counters, or compute interop. This allows the GPU to consume these arguments without a round- trip to the CPU or the expensive synchronization that would involve. This is similar to the DrawTransformFeedbackEXT command from EXT_transform_feedback2, but offers much more flexibility in both generating the arguments and in the type of Draws that can be accomplished.

Requires OpenGL 3.1. Promoted to core in OpenGL 4.0.

Field Summary

Fields

Modifier and Type	Field and Description
static int	GL_DRAW_INDIRECT_BUFFER Accepted by the target parameters of BindBuffer, BufferData, BufferSubData, MapBuffer, UnmapBuffer, GetBufferSubData, GetBufferPointerv, MapBufferRange, FlushMappedBufferRange, GetBufferParameteriv, and CopyBufferSubData.
static int	GL_DRAW_INDIRECT_BUFFER_BINDING Accepted by the value parameter of GetIntegerv, GetBooleanv, GetFloatv, and GetDoublev.

Method Summary

Modifier and Type	Method and Description
static void	glDrawArraysIndirect(int mode, java.nio.ByteBuffer indirect) Renders primitives from array data, taking parameters from memory.
static void	glDrawArraysIndirect(int mode, int[] indirect) Array version of: DrawArraysIndirect
static void	glDrawArraysIndirect(int mode, java.nio.IntBuffer indirect) Renders primitives from array data, taking parameters from memory.
static void	glDrawArraysIndirect(int mode, long indirect) Renders primitives from array data, taking parameters from memory.
static void	glDrawElementsIndirect(int mode, int type, java.nio.ByteBuffer indirect) Renders indexed primitives from array data, taking parameters from memory.
static void	glDrawElementsIndirect(int mode, int type, int[] indirect) Array version of: DrawElementsIndirect
static void	glDrawElementsIndirect(int mode, int type, java.nio.IntBuffer indirect) Renders indexed primitives from array data, taking parameters from memory.
static void	glDrawElementsIndirect(int mode, int type, long indirect) Renders indexed primitives from array data, taking parameters from memory.

Methods inherited from class java.lang.Object

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

Field Detail

GL_DRAW_INDIRECT_BUFFER

Accepted by the target parameters of BindBuffer, BufferData, BufferSubData, MapBuffer, UnmapBuffer, GetBufferSubData, GetBufferPointerv, MapBufferRange, FlushMappedBufferRange, GetBufferParameteriv, and CopyBufferSubData.

GL_DRAW_INDIRECT_BUFFER_BINDING

Accepted by the value parameter of GetIntegerv, GetBooleanv, GetFloatv, and GetDoublev.

Method Detail

glDrawArraysIndirect

public static void glDrawArraysIndirect(int mode,
                                        java.nio.ByteBuffer indirect)

public static void glDrawArraysIndirect(int mode,
                                        long indirect)

public static void glDrawArraysIndirect(int mode,
                                        java.nio.IntBuffer indirect)

Renders primitives from array data, taking parameters from memory.

glDrawArraysIndirect behaves similarly to DrawArraysInstancedBaseInstance, except that the parameters to glDrawArraysInstancedBaseInstance are stored in memory at the address given by indirect.

The parameters addressed by indirect are packed into a structure that takes the form (in C):

typedef struct {
    uint count;
    uint primCount;
    uint first;
    uint baseInstance; // must be 0 unless OpenGL 4.2 is supported
} DrawArraysIndirectCommand;

const DrawArraysIndirectCommand *cmd = (const DrawArraysIndirectCommand *)indirect;
glDrawArraysInstancedBaseInstance(mode, cmd->first, cmd->count, cmd->primCount, cmd->baseInstance);

Parameters:

mode - what kind of primitives to render. One of:

POINTS	LINE_STRIP	LINE_LOOP	LINES	POLYGON	TRIANGLE_STRIP	TRIANGLE_FAN
TRIANGLES	QUAD_STRIP	QUADS	LINES_ADJACENCY	LINE_STRIP_ADJACENCY	TRIANGLES_ADJACENCY	TRIANGLE_STRIP_ADJACENCY
PATCHES

indirect - a structure containing the draw parameters

glDrawElementsIndirect

public static void glDrawElementsIndirect(int mode,
                                          int type,
                                          java.nio.ByteBuffer indirect)

public static void glDrawElementsIndirect(int mode,
                                          int type,
                                          long indirect)

public static void glDrawElementsIndirect(int mode,
                                          int type,
                                          java.nio.IntBuffer indirect)

Renders indexed primitives from array data, taking parameters from memory.

glDrawElementsIndirect behaves similarly to DrawElementsInstancedBaseVertexBaseInstance, execpt that the parameters to glDrawElementsInstancedBaseVertexBaseInstance are stored in memory at the address given by indirect.

The parameters addressed by indirect are packed into a structure that takes the form (in C):

typedef struct {
    uint count;
    uint primCount;
    uint firstIndex;
    uint baseVertex;
    uint baseInstance;
} DrawElementsIndirectCommand;

glDrawElementsIndirect is equivalent to:

void glDrawElementsIndirect(GLenum mode, GLenum type, const void *indirect) {
    const DrawElementsIndirectCommand *cmd  = (const DrawElementsIndirectCommand *)indirect;
    glDrawElementsInstancedBaseVertexBaseInstance(
        mode,
        cmd->count,
        type,
        cmd->firstIndex + size-of-type,
        cmd->primCount,
        cmd->baseVertex,
        cmd->baseInstance
    );
}

Parameters:

mode - what kind of primitives to render. One of:

POINTS	LINE_STRIP	LINE_LOOP	LINES	POLYGON	TRIANGLE_STRIP	TRIANGLE_FAN
TRIANGLES	QUAD_STRIP	QUADS	LINES_ADJACENCY	LINE_STRIP_ADJACENCY	TRIANGLES_ADJACENCY	TRIANGLE_STRIP_ADJACENCY
PATCHES

type - the type of data in the buffer bound to the ELEMENT_ARRAY_BUFFER binding. One of:

UNSIGNED_BYTE

UNSIGNED_SHORT

UNSIGNED_INT

indirect - the address of a structure containing the draw parameters

glDrawArraysIndirect

public static void glDrawArraysIndirect(int mode,
                                        int[] indirect)

Array version of: DrawArraysIndirect

glDrawElementsIndirect

public static void glDrawElementsIndirect(int mode,
                                          int type,
                                          int[] indirect)

Array version of: DrawElementsIndirect