Implement instance uniforms in Compatibility renderer

drivers/gles3/rasterizer_scene_gles3.cpp

@@ -3453,6 +3453,7 @@ void RasterizerSceneGLES3::_render_list_template(RenderListParameters *p_params,
 			}
 
 			material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::MODEL_FLAGS, inst->flags_cache, shader->version, instance_variant, spec_constants);
+			material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::INSTANCE_OFFSET, uint32_t(inst->shader_uniforms_offset), shader->version, instance_variant, spec_constants);
 
 			if (p_pass_mode == PASS_MODE_MATERIAL) {
 				material_storage->shaders.scene_shader.version_set_uniform(SceneShaderGLES3::UV_OFFSET, p_params->uv_offset, shader->version, instance_variant, spec_constants);

drivers/gles3/shaders/scene.glsl

@@ -261,6 +261,7 @@ uniform highp mat4 world_transform;
 uniform highp vec3 compressed_aabb_position;
 uniform highp vec3 compressed_aabb_size;
 uniform highp vec4 uv_scale;
+uniform highp uint instance_offset;
 
 uniform highp uint model_flags;
 
@@ -965,6 +966,7 @@ ivec2 multiview_uv(ivec2 uv) {
 uniform highp mat4 world_transform;
 uniform mediump float opaque_prepass_threshold;
 uniform highp uint model_flags;
+uniform highp uint instance_offset;
 
 #if defined(RENDER_MATERIAL)
 layout(location = 0) out vec4 albedo_output_buffer;

drivers/gles3/storage/material_storage.cpp

@@ -1371,6 +1371,7 @@ MaterialStorage::MaterialStorage() {
 
 		actions.check_multiview_samplers = RasterizerGLES3::get_singleton()->is_xr_enabled();
 		actions.global_buffer_array_variable = "global_shader_uniforms";
+		actions.instance_uniform_index_variable = "instance_offset";
 
 		shaders.compiler_scene.initialize(actions);
 	}

servers/rendering/shader_compiler.cpp

@@ -949,7 +949,7 @@ String ShaderCompiler::_dump_node_code(const SL::Node *p_node, int p_level, Gene
 							code = _get_global_shader_uniform_from_type_and_index(p_default_actions.global_buffer_array_variable, code, u.type);
 						} else if (u.scope == ShaderLanguage::ShaderNode::Uniform::SCOPE_INSTANCE) {
 							//instance variable, index it as such
-							code = "(" + p_default_actions.instance_uniform_index_variable + "+" + itos(u.instance_index) + ")";
+							code = "(" + p_default_actions.instance_uniform_index_variable + "+" + itos(u.instance_index) + "u)";
 							code = _get_global_shader_uniform_from_type_and_index(p_default_actions.global_buffer_array_variable, code, u.type);
 						} else {
 							//regular uniform, index from UBO
@@ -1049,7 +1049,7 @@ String ShaderCompiler::_dump_node_code(const SL::Node *p_node, int p_level, Gene
 							code = _get_global_shader_uniform_from_type_and_index(p_default_actions.global_buffer_array_variable, code, u.type);
 						} else if (u.scope == ShaderLanguage::ShaderNode::Uniform::SCOPE_INSTANCE) {
 							//instance variable, index it as such
-							code = "(" + p_default_actions.instance_uniform_index_variable + "+" + itos(u.instance_index) + ")";
+							code = "(" + p_default_actions.instance_uniform_index_variable + "+" + itos(u.instance_index) + "u)";
 							code = _get_global_shader_uniform_from_type_and_index(p_default_actions.global_buffer_array_variable, code, u.type);
 						} else {
 							//regular uniform, index from UBO

servers/rendering/shader_language.cpp

@@ -9049,10 +9049,6 @@ Error ShaderLanguage::_parse_shader(const HashMap<StringName, FunctionInfo> &p_f
 						_set_error(vformat(RTR("Uniform instances are not yet implemented for '%s' shaders."), shader_type_identifier));
 						return ERR_PARSE_ERROR;
 					}
-					if (OS::get_singleton()->get_current_rendering_method() == "gl_compatibility") {
-						_set_error(RTR("Uniform instances are not supported in gl_compatibility shaders."));
-						return ERR_PARSE_ERROR;
-					}
 					if (uniform_scope == ShaderNode::Uniform::SCOPE_LOCAL) {
 						tk = _get_token();
 						if (tk.type != TK_UNIFORM) {