add initial GLES2 3D renderer

[karroffel]

This PR adds basic 3D rendering to the GLES2 backend. Many things are still buggy (directional shadows, normalmaps, some internal culling settings) and some things are ugly and need a refactor (light rendering and texture unit assignment). Other things are not yet implemented (Reflection probes, light maps).

Those things will be added in later PRs, this PR is just there to get some more people to test the backend.

Sooooo ~ happy testing! 💙

[BastiaanOlij]

Too cool man!

From earlier today:

You already mentioned the issue with shadows and the wheels are inside out. Other then that my vehicle demo project (https://github.com/BastiaanOlij/vehicle-demo) is working amazingly well using the GLES2 renderer (the trees aren't in the demo yet, just my copy).

[volzhs]

I got some error message with GLES 2.0 driver while running on Android (Galaxy S8+) which supports gles 2.0 and 3.0.

**ERROR**: SceneShaderGLES2: Fragment shader compilation failed:
1:1: P0003: Extension 'GL_ARB_shader_texture_lod' not supported
1:54: L0002: No matching function for call to 'texture2DLod'
   At: drivers/gles2/shader_gles2.cpp:457:get_current_version() - SceneShaderGLES2: Fragment shader compilation failed:
1:1: P0003: Extension 'GL_ARB_shader_texture_lod' not supported
1:54: L0002: No matching function for call to 'texture2DLod'
**ERROR**: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:466:get_current_version() - Method/Function Failed, returning: __null
**ERROR**: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:133:bind() - Condition ' !version ' is true. returned: false
**ERROR**: SceneShaderGLES2: Fragment shader compilation failed:
1:1: P0003: Extension 'GL_ARB_shader_texture_lod' not supported
1:54: L0002: No matching function for call to 'texture2DLod'
   At: drivers/gles2/shader_gles2.cpp:457:get_current_version() - SceneShaderGLES2: Fragment shader compilation failed:
1:1: P0003: Extension 'GL_ARB_shader_texture_lod' not supported
1:54: L0002: No matching function for call to 'texture2DLod'
**ERROR**: Method/Function Failed, returning: __null
   At: drivers/gles2/shader_gles2.cpp:466:get_current_version() - Method/Function Failed, returning: __null
**ERROR**: Condition ' !version ' is true. returned: false
   At: drivers/gles2/shader_gles2.cpp:133:bind() - Condition ' !version ' is true. returned: false

as result, some texture is not shown with shader.

shader_type canvas_item;

render_mode blend_mix;
uniform float fattyness = 1.0;

void fragment(){
	vec2 ruv = UV - vec2(0.5,0.5);
	vec2 dir = normalize(ruv);
	float len = length(ruv);	
	
	len = pow(len*2.0, fattyness)*0.5;
	ruv = len*dir;
	
	vec4 col = texture(TEXTURE, ruv + vec2(0.5, 0.5));
	
	COLOR = col;
}

[karroffel]

@volzhs The problem is not your shader, if you look at the error log, it says it's SceneShaderGLES2.

It is weird that it makes the textures not show up, are you embedding things in a 3D world by any chance?

Unfortunately there is not a good way around that, since GLSL ES 1.0 doesn't allow texture2DLod in fragment shaders. I could wrap it in a preprocessor define if the object is unshaded.

But yeah, for now there is no way around that that I know of.

[volzhs]

I'm only using 2D.

[karroffel]

Let's merge this thing and move bugs into separate issue trackers 😉

[volzhs]

the shader codes I posted came from https://github.com/godotengine/godot-demo-projects/tree/master/2d/sprite_shaders
so, yes, need a way to workaround.

ok, then let me create an issue about that.