GPU/EEVEE: Refactor codegen and nodetree support

This is the first step towards the new evaluation scheme of EEVEE
closures.

This commit contains:
- Removal of GPU_SOURCE_BUILTIN type, prefering global instead. This
  avoid many boilerplate code since most of the old builtins are now
  datas that are always present (i.e: view matrices, normals).
- Rewritting of codegen in C++ to use `std::stringstream`.
- Added a callback to let engine decide what to do with codegen code.
  This remove a lot of needs for defines because of code order
  dependency. The engine can insert the nodetree code in custom ways
  to create advance effects (i.e: add displacement or vertex lighting).
  Engine now returns final shader strings.
- Closure nodes evaluation replacment is a placeholder for now.

1 files changed, 15 insertions, 5 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_shader.hh b/source/blender/draw/engines/eevee/eevee_shader.hh
index d3e4284da1f..325d370d2c4 100644
--- a/source/blender/draw/engines/eevee/eevee_shader.hh
+++ b/source/blender/draw/engines/eevee/eevee_shader.hh
@@ -115,19 +115,29 @@ class ShaderModule {
   ~ShaderModule();
 
   GPUShader *static_shader_get(eShaderType shader_type);
-  GPUMaterial *material_shader_get(Scene *scene,
-                                   ::Material *blender_mat,
+  GPUMaterial *material_shader_get(::Material *blender_mat,
+                                   struct bNodeTree *nodetree,
                                    eMaterialGeometry geometry_type,
                                    eMaterialDomain domain_type,
                                    bool deferred_compilation);
 
+  GPUShaderSource material_shader_code_generate(GPUMaterial *mat, const GPUCodegenOutput *codegen);
+
  private:
   /* Run some custom preprocessor shader rewrite and returns a new string. */
   std::string enum_preprocess(const char *input);
 
-  std::string material_shader_code_defs_get(eMaterialDomain domain_type);
-  char *material_shader_code_vert_get(eMaterialGeometry geometry_type);
-  char *material_shader_code_frag_get(eMaterialGeometry geometry_type,
+  char *material_shader_code_defs_get(eMaterialDomain domain_type);
+  char *material_shader_code_vert_get(const GPUCodegenOutput *codegen,
+                                      GPUMaterial *mat,
+                                      eMaterialGeometry geometry_type);
+  char *material_shader_code_geom_get(const GPUCodegenOutput *codegen,
+                                      GPUMaterial *mat,
+                                      eMaterialGeometry geometry_type,
+                                      eMaterialDomain domain_type);
+  char *material_shader_code_frag_get(const GPUCodegenOutput *codegen,
+                                      GPUMaterial *mat,
+                                      eMaterialGeometry geometry_type,
                                       eMaterialPipeline pipeline_type);
 };