Chapter 11 advanced data management of OpenGL super classic (version 7)

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Preface

How to write data from shaders to cache and textures
How to make Opengl More flexible interpretation of data
CPU And GPU How to share data directly

One 、 Unbind

sketch ： Disassociate the sampler variable from the texture unit , Use texture handles instead of
reason ：1. The number of textures that a single shader can access is limited 2. Binding and unbinding take time
usage ： Use GL_ARB_bindless_texture Expand , Use texture to generate texture handles , Put the texture into resident memory through the texture handle
GLuint64 glGetTextureHandleARB()： Use texture to generate texture handles and return to texture handles
GLuint64 glGetTextureSamplerHandleARB()： Bound texture unit , Returns the texture handle
void glMakeTextureHandleResidentARB()： Put the texture into resident memory through the texture handle
void glMakeTextureHandleNonResidentARB()： Move the texture out of resident memory through the texture handle

Two 、 Sparse texture

sketch ： Divide the texture into multiple rows or rectangular areas , The user can control the display of these areas , Commonly used in game maps
page ： One of a plurality of square rows or rectangular regions into which a texture is divided
Transfer page ： You can use it like a normal texture
No transfer page ： The texture of this area is not stored
To use sparse textures, use GL_ARB_sparse_texture Expand , And before allocating memory for the texture , To use glTextureParameteri() Statement
Example ： Stream texture data in chronological order （ People words ： The first time a player starts a game is , High resolution close to the player , Far away from the player , The distance is mapped to the level of detail of texture extraction ）

3、 ... and 、 Compress texture

sketch ： Use RGTC Compress the texture into small independent data blocks , Because data blocks are independent of each other , When decompressing, it can be placed in single thread parallel decompression
Compressed format ： Data blocks ,（ Like other compressed formats ）
The compression ratio is fixed
The compression effect is not very good , But suitable for random access , And lossless compression
Suitable for images with smooth areas

Four 、 Compressed data format

sketch ：opengl Supported compressed data formats , for example ：GL_UNSIGNED_SHORT_5_6_5

5、 ... and 、 High quality texture filtering

Linear filtering and closest filtering
Closest to filtering ： Select the texture element whose sampling point is closest to the texture coordinate
Linear filtering ： The filtering method is linear interpolation , High quality , Shaders use smooth interpolation functions smoothstep() It can optimize the artifacts of enlarged texture images

summary

Unbound texture ： You can make shaders have an unlimited number of textures
Sparse texture ： Manage the memory allocated to each texture object
Compress texture ： Improve texture resource utilization
High quality texture filtering ： Optimize linear filtering details , Improve image quality