OpenGLES3.0 API速查指南：异步查询与缓冲对象

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“opengles3-quick-reference-card.pdf”是一个关于OpenGL ES 3.0 API的快速参考卡片，由Khronos Group于2012年发布。它涵盖了异步查询、缓冲对象等多个关键概念。在OpenGL ES 3.0中，异步查询是一个重要的特性，允许开发者在不阻塞主线程的情况下获取图形处理单元（GPU）的状态信息。这有助于提高应用性能和响应性。以下是关于异步查询的关键点： 1. `void GenQueries(sizein,uint*ids);`：此函数用于生成一个或多个查询对象标识符。这些对象将被用于执行特定类型的查询。 2. `void BeginQuery(enumtarget,uint id);`：启动一个查询，指定查询类型（如`ANY_SAMPLES_PASSED_CONSERVATIVE`，用于检查帧缓冲区中的所有样本是否都通过了深度测试）。`id`是之前生成的查询对象的标识符。 3. `void EndQuery(enumtarget);`：结束当前正在执行的查询。当调用`EndQuery`时，GPU会继续执行查询，但不会阻塞CPU。 4. `void DeleteQueries(sizein,const uint*ids);`：删除不再需要的查询对象。 5. `boolean IsQuery(uint id);`：检查给定的标识符是否表示一个有效的查询对象。 6. `void GetQueryiv(enum target,enumpname,int*params);` 和 `void GetQueryObjectuiv(uint id,enumpname,uint*params);`：这两个函数用于获取查询对象的参数，例如查询结果或其他元数据。除了异步查询，OpenGL ES 3.0还引入了缓冲对象（Buffer Objects），它们是存储顶点数组数据或索引的高性能服务器内存。缓冲对象的主要操作包括： 1. `void GenBuffers(sizein,uint*buffers);` 和 `void DeleteBuffers(sizein,const uint*buffers);`：生成和删除缓冲对象。 2. `void BindBuffer(enum target,uint buffer);`：绑定一个缓冲对象到特定的目标，如顶点数组（VERTEX_ARRAY_BUFFER）、像素打包（PIXEL_UNPACK_BUFFER）或像素解包（PIXEL_PACK_BUFFER）等。 3. `void BindBufferRange(enum target,uint index,uint buffer,int ptroffset,sizeiptrsize);` 和 `void BindBufferBase(enum target,uint index,uint buffer);`：用于将缓冲对象绑定到指定的缓冲目标索引，可以设置偏移量和大小（针对UNIFORM_BUFFER或TRANSFORM_FEEDBACK_BUFFER等目标）。这些API调用允许开发者有效地管理图形数据，提高渲染效率，并利用OpenGL ES 3.0的高级特性，如统一缓冲（UNIFORM_BUFFER）和变换反馈（TRANSFORM_FEEDBACK_BUFFER），进一步优化图形处理。

OpenGL ES 3.0 API Reference Card Page 1

Asynchronous Queries

[2.13, 6.1.7]

void GenQueries(sizei n, uint *ids);

void BeginQuery(enum target, uint id);

target: ANY_SAMPLES_PASSED{_CONSERVATIVE}

void EndQuery(enum target);

target: ANY_SAMPLES_PASSED{_CONSERVATIVE}

void DeleteQueries(sizei n, const uint *ids);

boolean IsQuery(uint id);

void GetQueryiv(enum target, enum pname,

int *params);

void GetQueryObjectuiv(uint id, enum pname,

uint *params);

Buer Objects

[2.9]

Buer objects hold vertex array data or indices in

high-performance server memory.

void GenBuers(sizei n, uint *buers);

void DeleteBuers(sizei n, const uint *buers);

Creang and Binding Buer Objects

void BindBuer(enum target, uint buer);

target: {ELEMENT_}ARRAY_BUFFER, PIXEL_{UN}PACK_BUFFER,

COPY_{READ, WRITE}_BUFFER, UNIFORM_BUFFER,

TRANSFORM_FEEDBACK_BUFFER

void BindBuerRange(enum target, uint index,

uint buer, intptr oset, sizeiptr size);

target: TRANSFORM_FEEDBACK_BUFFER, UNIFORM_BUFFER

void BindBuerBase(enum target, uint index, uint buer);

target: TRANSFORM_FEEDBACK_BUFFER, UNIFORM_BUFFER

Creang Buer Object Data Stores

void BuerData(enum target, sizeiptr size,

const void *data, enum usage);

target: See BindBuer

usage: {STATIC, STREAM, DYNAMIC}_{DRAW, READ, COPY}

void BuerSubData(enum target, intptr oset,

sizeiptr size, const void *data);

target: See BindBuer

Mapping and Unmapping Buer Data

void *MapBuerRange(enum target, intptr oset,

sizeiptr length, biield access);

target: See BindBuer

access: Bitwise OR of MAP_{READ, WRITE}_BIT,

MAP_INVALIDATE_{RANGE, BUFFER_BIT},

MAP_FLUSH_EXPLICIT_BIT, MAP_UNSYNCHRONIZED_BIT

void FlushMappedBuerRange(enum target,

intptr oset, sizeiptr length);

target: See BindBuer

boolean UnmapBuer(enum target);

target: See BindBuer

Copying Between Buers

void CopyBuerSubData(enum readtarget,

enum writetarget, intptr readoset, intptr writeoset,

sizeiptr size);

readtarget, writetarget: See target for BindBuer

Buer Object Queries [6.1.9]

boolean IsBuer(uint buer);

void GetBuerParameteriv(enum target, enum pname,

int * data);

target: See BindBuer

pname: BUFFER_{SIZE, USAGE, ACCESS_FLAGS, MAPPED},

BUFFER_ MAP_{POINTER, OFFSET, LENGTH}

void GetBuerParameteri64v(enum target,

enum pname, int64 *data);

target, pname: See

GetBuerParameteriv

void GetBuerPointerv(enum target, enum pname,

void **params);

target: See BindBuer

pname: BUFFER_ MAP_POINTER

OpenGL

ES is a soware interface to graphics hardware. The interface consists

of a set of procedures and funcons that allow a programmer to specify the

objects and operaons involved in producing high-quality graphical images,

specically color images of three-dimensional objects.

• [n.n.n] refers to secons and tables in the OpenGL ES 3.0 specicaon.

• [n.n.n] refers to secons in the OpenGL ES Shading Language 3.0 specicaon.

Specicaons are available at www.khronos.org/registry/gles/

OpenGL ES Command Syntax [2.3]

Open GL ES commands are formed from a return type, a name, and oponally a type leer: i for 32-bit int, i64 for int64,

f for 32-bit oat, or ui for 32-bit uint, as shown by the prototype below:

return-type Name{1234}{i i64 f ui}{v} ([args ,] T arg1 , . . . , T argN [, args]);

The arguments enclosed in brackets ([args ,] and [, args]) may or may not be present.

The argument type T and the number N of arguments may be indicated by the command name suxes. N is 1, 2, 3, or 4 if

present. If “v” is present, an array of N items is passed by a pointer.

For brevity, the OpenGL documentaon and this reference may omit the standard prexes.

The actual names are of the forms: glFunconName(), GL_CONSTANT, GLtype

Errors [2.5]

enum GetError(void);

//Returns one of the following:

NO_ERROR No error encountered

INVALID_ENUM Enum argument out of range

INVALID_VALUE Numeric argument out of range

INVALID_OPERATION Operaon illegal in current state

INVALID_FRAMEBUFFER_OPERATION Framebuer is incomplete

OUT_OF_MEMORY Not enough memory le to execute command

Viewport and Clipping

[2.12.1]

void DepthRangef(oat n, oat f);

void Viewport(int x, int y, sizei w, sizei h);

GL Data Types [2.3]

GL types are not C types.

GL Type

Minimum

Bit Width Descripon

boolean 1 Boolean

byte 8 Signed 2’s complement binary integer

ubyte 8 Unsigned binary integer

char 8 Characters making up strings

short 16 Signed 2’s complement binary integer

ushort 16 Unsigned binary integer

int 32 Signed 2’s complement binary integer

uint 32 Unsigned binary integer

int64 64 Signed 2’s complement binary integer

uint64 64 Unsigned binary integer

xed 32 Signed 2’s complement 16.16 scaled integer

sizei 32 Non-negave binary integer size

enum 32 Enumerated binary integer value

intptr ptrbits Signed 2’s complement binary integer

sizeiptr ptrbits Non-negave binary integer size

sync ptrbits Sync object handle

biield 32 Bit eld

half 16 Half-precision oat encoded in unsigned scalar

oat 32 Floang-point value

clampf 32 Floang-point value clamped to [0, 1]

Reading and Copying Pixels

[4.3.1-2]

void ReadPixels(int x, int y, sizei width, sizei height,

enum format, enum type, void *data);

format: RGBA, RGBA_INTEGER

type

: INT, UNSIGNED_INT_2_10_10_10_REV, UNSIGNED_{BYTE, INT}

Note: ReadPixels() also accepts a queriable implementaon-

chosen format/type combinaon [4.3.1]

void ReadBuer(enum src);

src: BACK, NONE, or COLOR_ATTACHMENT

where i may range

from zero to the value of MAX_COLOR_ATTACHMENTS - 1

void BlitFramebuer(int srcX0, int srcY0, int srcX1,

int srcY1, int dstX0, int dstY0, int dstX1, int dstY1,

biield mask, enum lter);

mask: Bitwise OR of {COLOR, DEPTH, STENCIL}_BUFFER_BIT

lter: LINEAR or NEAREST

Verces

Current Vertex State [2.7]

void VertexArib{1234}f(uint index, oat values);

void VertexArib{1234}fv(uint index, const oat *values);

void VertexAribl4{i ui}(uint index, T values);

void VertexAribl4{i ui}v(uint index, const T values);

Vertex Arrays [2.8]

Vertex data may be sourced from arrays stored in client’s address

space (via a pointer) or in server’s address space (in a buer object).

void VertexAribPointer(uint index, int size, enum type,

boolean normalized, sizei stride, const void *pointer);

type: {UNSIGNED_}BYTE, {UNSIGNED_}SHORT, {UNSIGNED_}INT, FIXED,

{HALF_}FLOAT, {UNSIGNED_}INT_2_10_10_10_REV

index: [0, MAX_VERTEX_ATTRIBS - 1]

void VertexAribIPointer(uint index, int size, enum type,

sizei stride, const void *pointer);

type: {UNSIGNED_}BYTE, {UNSIGNED_}SHORT, {UNSIGNED_}INT

index: [0, MAX_VERTEX_ATTRIBS - 1]

void EnableVertexAribArray(uint index);

void DisableVertexAribArray(uint index);

void VertexAribDivisor(uint index, uint divisor);

index: [0, MAX_VERTEX_ATTRIBS - 1]

void Enable(enum target);

void Disable(enum target);

target: PRIMITIVE_RESTART_FIXED_INDEX

Drawing [2.8.3]

void DrawArrays(enum mode, int rst, sizei count);

void DrawArraysInstanced(enum mode, int rst, sizei count,

sizei primcount);

void DrawElements(enum mode, sizei count, enum type,

const void *indices);

type: UNSIGNED_BYTE, UNSIGNED_SHORT, UNSIGNED_INT

void DrawElementsInstanced(enum mode, sizei count,

enum type, const void *indices, sizei primcount);

type: UNSIGNED_BYTE, UNSIGNED_SHORT, UNSIGNED_INT

void DrawRangeElements(enum mode, uint start, uint end,

sizei count, enum type, const void *indices);

mode: POINTS, TRIANGLES, LINES, LINE_{STRIP, LOOP}, TRIANGLE_STRIP,

TRIANGLE_FAN

type: UNSIGNED_BYTE, UNSIGNED_SHORT, UNSIGNED_INT

Vertex Array Objects

[2.10, 6.1.10]

void GenVertexArrays(sizei n, uint *arrays);

void DeleteVertexArrays(sizei n, const uint *arrays);

void BindVertexArray(uint array);

boolean IsVertexArray(uint array);

Rasterizaon [3]

Points [3.4]

Point size is taken from the shader built-in gl_PointSize and

clamped to the implementaon-dependent point size range.

Line Segments [3.5]

void LineWidth(oat width);

Polygons [3.6]

void FrontFace(enum dir);

dir: CCW, CW

void CullFace(enum mode);

mode: FRONT, BACK, FRONT_AND_BACK

Enable/Disable(CULL_FACE);

void PolygonOset(oat factor, oat units);

Enable/Disable(POLYGON_OFFSET_FILL);

Transform Feedback

[2.14, 6.1.11]

void GenTransformFeedbacks(sizei n, uint *ids);

void DeleteTransformFeedbacks(sizei n,

const uint *ids);

void BindTransformFeedback(enum target, uint id);

target: TRANSFORM_FEEDBACK

void BeginTransformFeedback(enum primiveMode);

primiveMode: TRIANGLES, LINES, POINTS

void EndTransformFeedback(void);

void PauseTransformFeedback(void);

void ResumeTransformFeedback(void);

boolean IsTransformFeedback(uint id);

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