Godot: GLES2 Shader Bug with Dissolve Shader

[DleanJeans]

Godot version: 3.1.1

OS/device including version:

• Windows 10 64-bit
• Intel(R) HD Graphics 4000

Issue description:

First row: My game project
Second row: Minimal project

GLES3 | GLES2
:---:|:---:
|
|

Steps to reproduce: Just enable GLES2

(Optionally follow Dissolve Shader tutorial by GDquest by yourself)

Minimal reproduction project:

DissolveShader.zip
The project is currently in GLES3 mode. Switch to GLES2 at your own risk!

[clayjohn]

I can't reproduce. Linux 16.04 intel integrated graphics Mesa 18.0.5.

Have you tried updating your drivers?

[DleanJeans]

Updated. Still happens.

[clayjohn]

Do you get any errors appearing in the console when you switch to GLES2?

[DleanJeans]

Yes, first it prints thousands of what seem to be GLSL code, starting with:

1: #version 120
2: #define USE_GLES_OVER_GL
3: #define ENABLE_UV_INTERP
...
1550:

ERROR: _display_error_with_code: SceneShaderGLES2: Fragment shader compilation failed:
ERROR: 8:22: 'round' : no matching overloaded function found (using implicit conversion)


   At: drivers/gles2/shader_gles2.cpp:129
ERROR: get_current_version: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:364
ERROR: bind: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:88

1: #version 120
2: #define USE_GLES_OVER_GL
3: #define USE_RADIANCE_MAP
4: #define BASE_PASS
5: #define ENABLE_UV_INTERP
...
1552:



md5-2af6f80956198fbaa3f882af135e9edd



ERROR: _display_error_with_code: SceneShaderGLES2: Fragment shader compilation failed:
ERROR: 10:22: 'round' : no matching overloaded function found (using implicit conversion)


   At: drivers/gles2/shader_gles2.cpp:129
ERROR: get_current_version: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:364
ERROR: bind: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:88
ERROR: _get_uniform: Condition ' !version ' is true. returned: -1
   At: drivers/gles2/shader_gles2.h:254
ERROR: _get_uniform: Condition ' !version ' is true. returned: -1
   At: drivers/gles2/shader_gles2.h:254  # 12 more times



md5-2af6f80956198fbaa3f882af135e9edd



... I'll just skip the GLSL code



md5-2af6f80956198fbaa3f882af135e9edd



ERROR: _display_error_with_code: SceneShaderGLES2: Fragment shader compilation failed:
ERROR: 11:22: 'round' : no matching overloaded function found (using implicit conversion)
ERROR: 12:222: 'L' : undeclared identifier
ERROR: 12:222: 'assign' :  cannot convert from '3-component vector of float' to 'float'
ERROR: 12:519: 'light_compute' : no matching overloaded function found (using implicit conversion)


   At: drivers/gles2/shader_gles2.cpp:129
ERROR: get_current_version: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:364
ERROR: bind: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:88
ERROR: _get_uniform: Condition ' !version ' is true. returned: -1
   At: drivers/gles2/shader_gles2.h:254



md5-2af6f80956198fbaa3f882af135e9edd



... more GLSL



md5-2af6f80956198fbaa3f882af135e9edd



ERROR: _display_error_with_code: SceneShaderGLES2: Fragment shader compilation failed:
ERROR: 10:22: 'round' : no matching overloaded function found (using implicit conversion)
ERROR: 11:222: 'L' : undeclared identifier
ERROR: 11:222: 'assign' :  cannot convert from '3-component vector of float' to 'float'
ERROR: 11:519: 'light_compute' : no matching overloaded function found (using implicit conversion)


   At: drivers/gles2/shader_gles2.cpp:129
ERROR: get_current_version: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:364
ERROR: bind: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:88
ERROR: _get_uniform: Condition ' !version ' is true. returned: -1
   At: drivers/gles2/shader_gles2.h:254

[clayjohn]

Thank you! That was exactly the information I needed.

The issue is that you are using the function round which is not in GLES2. It is documented here: http://docs.godotengine.org/en/latest/tutorials/misc/gles2_gles3_differences.html.

The way OpenGL works is that individual driver vendors choose what functions to implement, but they have to have at least the basic specification. So, on my computer round is supported even in GLES2 (but it shouldn't be). Your drivers are extra strict and are not letting you use a function not found in the core specification.

In version 3.2 the visual shader has a description next to the name of functions letting you know if you can use them in GLES2 or not.

[DleanJeans]

Any workaround for this round function?

[clayjohn]

Sure! Just add 0.5 then use floor it does the exact same thing!

In VisualShaders, the process is: add a scalarOp, set to add. connect the result from your subtraction to input a set input b to 0.5. Then connect the result to another scalarOp set to floor. Use the result of floor as alpha.