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.
“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.
Particles and Particles2D can be converted to their CPU equivalent node with the “Convert to CPUParticles” option in the editor.
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.
While GLES2 supports
DEPTH_TEXTURE in shaders, it may not work on some old hardware (especially mobile).
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
statement check and see if the output is in sRGB, using
true in GLES2 and
false in GLES3.
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
In GLES2, the following advanced rendering features in the SpatialMaterial are missing:
- Subsurface scattering
- 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.
In GLES2, the following features in the Environment are missing:
- Auto exposure
- Screen space reflections
- Screen space ambient occlusion
That means that in GLES2 environments you can only set:
- Sky (including procedural sky)
- Ambient light
- Depth of field
- Glow (also known as bloom)
shadow_contact property of Lights is not supported in GLES2 and so does nothing.
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.
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.
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 are not supported in GLES2.
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.
|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 )|
Functions not in GLES2’s GLSL were added with Godots own shader standard library. These functions may perform worse in GLES2 compared to GLES3.
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|