Differences between GLES2 and GLES3

This page documents the differences between GLES2 and GLES3 that are by design and are not the result of bugs. There may be differences that are unintentional, but they should be reported as bugs.

주석

"GLES2" and "GLES3" are the names used in Godot for the two OpenGL-based rendering backends. In terms of graphics APIs, the GLES2 backend maps to OpenGL 2.1 on desktop, OpenGL ES 2.0 on mobile and WebGL 1.0 on the web. The GLES3 backend maps to OpenGL 3.3 on desktop, OpenGL ES 3.0 on mobile and WebGL 2.0 on the web.

파티클

GLES2 cannot use the Particles or Particles2D nodes as they require advanced GPU features. Instead, use CPUParticles or CPUParticles2D, which provides a similar interface to a ParticlesMaterial.

참고

Particles and Particles2D can be converted to their CPU equivalent node with the "Convert to CPUParticles" option in the editor.

SCREEN_TEXTURE mip-maps

In GLES2, SCREEN_TEXTURE (accessed via a ShaderMaterial) does not have computed mip-maps. So when accessing at a different LOD, the texture will not appear blurry.

DEPTH_TEXTURE

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

Color space

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

GLES 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.

SpatialMaterial features

In GLES2, the following advanced rendering features in the SpatialMaterial are missing:

  • Refraction
  • Subsurface scattering
  • Anisotropy
  • Clearcoat
  • Depth mapping

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:

  • Auto exposure
  • Tonemapping
  • Screen space reflections
  • Screen space ambient occlusion

That means that in GLES2 environments you can only set:

  • Sky (including procedural sky)
  • Ambient light
  • Fog
  • Depth of field
  • Glow (also known as bloom)
  • Adjustment

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.

경고

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.

Shading language

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.

Function  
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 )  

주석

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