Отличия между GLES2 и GLES3

Эта страница описывает различия между GLES2 и GLES3 по дизайну а не в результате ошибок. Существует и много непреднамеренных различий, но о них нужно сообщить как об ошибках.

Примечание

"GLES2" и "GLES3" это имена используемые в Godot для двух базирующихся на OpenGL движка отрисовки. В терминологии графических API, движок GLES2 представляет OpenGL 2.1 на десктопе, OpenGL ES 2.0 на мобильных платформах и WebGL 1.0 в вэбе. Движок GLES3 - это OpenGL 3.3 на десктопе, OpenGL ES 3.0 на мобильных платформах и WebGL 2.0 в вэбе.

Частицы

В GLES2 нельзя использовать ноды Particles или Particles2D так как им требуется продвинутые возможности GPU. Вместо них, используйте CPUParticles или CPUParticles2D которые предоставляют похожий интерфейс для ParticlesMaterial.

Совет

Particles и Particles2D могут быть сконвертированы в эквивалент на CPU через опцию "Convert to CPUParticles" в редакторе.

SCREEN_TEXTURE mip-maps

В GLES2, SCREEN_TEXTURE (доступно через ShaderMaterial) не содержит вычисленных мип-карт. Так что при доступе к другому LOD, текстура не будет выглядеть сглаженной.

DEPTH_TEXTURE

While GLES2 supports DEPTH_TEXTURE in shaders, it may not work on some old hardware (especially mobile).

Цветовое пространство

GLES2 and GLES3 are in different color spaces. This means that colors will appear slightly different between them especially when lighting is used.

If your game is going to use both GLES2 and GLES3, you can use an if statement check and see if the output is in sRGB, using OUTPUT_IS_SRGB. OUTPUT_IS_SRGB is true in GLES2 and false in GLES3.

HDR

GLES2 is not capable of using High Dynamic Range (HDR) rendering features. If HDR is set for your project, or for a given viewport, Godot will still user Low Dynamic Range (LDR) which limits viewport values to the 0-1 range.

Возможности SpatialMaterial

В GLES2, следующие продвинутые возможности отрисовки отсутствуют в SpatialMaterial:

  • Refraction

  • Subsurface scattering

  • Anisotropy

  • Clearcoat

  • Отображение глубины

When using SpatialMaterials they will not even appear in the editor.

In custom ShaderMaterials, you can set values for these features but they will be non-functional. For example, you will still be able to set the SSS built-in (which normally adds subsurface scattering) in your shader, but nothing will happen.

Environment features

In GLES2, the following features in the Environment are missing:

  • Авто экспозиция

  • Тонирование

  • Отражения в экранном пространстве

  • Screen space ambient occlusion

Это означает что в среде GLES2 вы можете установить только:

  • Небо (включая процедурное небо)

  • Окружающий свет

  • Fog

  • Глубина резкости

  • Сияние (также известное как блюм)

  • Регулировка параметров цвета

GIProbes

GIProbes do not work in GLES2. Instead use Baked Lightmaps. For a description of how baked lightmaps work see the Baked Lightmaps tutorial.

Contact shadows

The shadow_contact property of Lights is not supported in GLES2 and so does nothing.

Light performance

In GLES2, performance scales poorly with several lights, as each light is processed in a separate render pass (in opposition to GLES3 which is all done in a single pass). Try to limit scenes to as few lights as possible in order to achieve greatest performance.

Texture compression

On mobile, GLES2 requires ETC texture compression, while GLES3 requires ETC2. ETC2 is enabled by default, so if exporting to mobile using GLES2 make sure to set the project setting rendering/vram_compression/import_etc and then reimport textures.

Предупреждение

Since ETC doesn't support transparency, you must reimport textures that contain an alpha channel to use the Uncompressed, Lossy or Lossless compression mode (instead of Video RAM). This can be done in the Import dock after selecting them in the FileSystem dock.

Blend shapes

Blend shapes are not supported in GLES2.

Язык шейдеров

GLES3 provides many built-in functions that GLES2 does not. Below is a list of functions that are not available or are have limited support in GLES2.

For a complete list of built-in GLSL functions see the Shading Language doc.

Функция

vec_type modf ( vec_type x, out vec_type i )

vec_int_type floatBitsToInt ( vec_type x )

vec_uint_type floatBitsToUint ( vec_type x )

vec_type intBitsToFloat ( vec_int_type x )

vec_type uintBitsToFloat ( vec_uint_type x )

ivec2 textureSize ( sampler2D_type s, int lod )

See workaround below

ivec2 textureSize ( samplerCube s, int lod )

See workaround below

vec4_type texture ( sampler_type s, vec_type uv [, float bias] )

bias not available in vertex shader

vec4_type textureProj ( sampler_type s, vec_type uv [, float bias] )

vec4_type textureLod ( sampler_type s, vec_type uv, float lod )

Only available in vertex shader on some hardware

vec4_type textureProjLod ( sampler_type s, vec_type uv, float lod )

vec4_type textureGrad ( sampler_type s, vec_type uv, vec_type dPdx, vec_type dPdy)

vec_type dFdx ( vec_type p )

vec_type dFdy ( vec_type p )

vec_type fwidth ( vec_type p )

Примечание

Functions not in GLES2's GLSL were added with Godots own shader standard library. These functions may perform worse in GLES2 compared to GLES3.

textureSize() workaround

GLES2 does not support textureSize(). You can get the size of a texture the old fashioned way by passing in a uniform with the texture size yourself.

// In the shader:
uniform sampler2D textureName;
uniform vec2 textureName_size;
# In GDScript:
material_name.set_shader_param("textureName", my_texture)
material_name.set_shader_param("textureName_size", my_texture_size)

Built in variables and render modes

Godot also provides many built-in variables and render modes. Some cannot be supported in GLES2. Below is a list of built-in variables and render modes that, when written to, will have no effect or could even cause issues when using the GLES2 backend.

Variable / Render Mode

ensure_correct_normals

INSTANCE_ID

DEPTH

ANISOTROPY

ANISOTROPY_FLOW

SSS_STRENGTH