GPU: Make nodetree GLSL Codegen render engine agnostic

This commit removes all EEVEE specific code from the `gpu_shader_material*.glsl`
files. It defines a clear interface to evaluate the closure nodes leaving
more flexibility to the render engine.

Some of the long standing workaround are fixed:
- bump mapping support is no longer duplicating a lot of node and is instead
  compiled into a function call.
- bump rewiring to Normal socket is no longer needed as we now use a global
  `g_data.N` for that.


Closure sampling with upstread weight eval is now supported if the engine needs
it.

This also makes all the material GLSL sources use `GPUSource` for better
debugging experience. The `GPUFunction` parsing now happens in `GPUSource`
creation.

The whole `GPUCodegen` now uses the `ShaderCreateInfo` and is object type
agnostic. Is has also been rewritten in C++.

This patch changes a view behavior for EEVEE:
- Mix shader node factor imput is now clamped.
- Tangent Vector displacement behavior is now matching cycles.
- The chosen BSDF used for SSR might change.
- Hair shading may have very small changes on very large hairs when using hair
  polygon stripes.
- ShaderToRGB node will remove any SSR and SSS form a shader.
- SSS radius input now is no longer a scaling factor but defines an average
  radius. The SSS kernel "shape" (radii) are still defined by the socket default
  values.

Appart from the listed changes no other regressions are expected.

3 files changed, 65 insertions, 16 deletions

diff --git a/source/blender/draw/intern/shaders/common_attribute_lib.glsl b/source/blender/draw/intern/shaders/common_attribute_lib.glsl
new file mode 100644
index 00000000000..99db2929a13
--- /dev/null
+++ b/source/blender/draw/intern/shaders/common_attribute_lib.glsl
@@ -0,0 +1,21 @@
+
+/* Prototype of functions to implement to load attributes data.
+ * Implementation changes based on object data type. */
+
+vec3 attr_load_orco(vec4 orco);
+vec4 attr_load_tangent(vec4 tangent);
+vec3 attr_load_uv(vec3 uv);
+vec4 attr_load_color(vec4 color);
+vec4 attr_load_vec4(vec4 attr);
+vec3 attr_load_vec3(vec3 attr);
+vec2 attr_load_vec2(vec2 attr);
+float attr_load_float(float attr);
+
+vec3 attr_load_orco(samplerBuffer orco);
+vec4 attr_load_tangent(samplerBuffer tangent);
+vec3 attr_load_uv(samplerBuffer uv);
+vec4 attr_load_color(samplerBuffer color);
+vec4 attr_load_vec4(samplerBuffer attr);
+vec3 attr_load_vec3(samplerBuffer attr);
+vec2 attr_load_vec2(samplerBuffer attr);
+float attr_load_float(samplerBuffer attr);
diff --git a/source/blender/draw/intern/shaders/common_math_lib.glsl b/source/blender/draw/intern/shaders/common_math_lib.glsl
index 4d0ffaeb40f..1ac26c91b93 100644
--- a/source/blender/draw/intern/shaders/common_math_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_math_lib.glsl
@@ -1,4 +1,8 @@
 
+/* WORKAROUND: to guard against double include in EEVEE. */
+#ifndef COMMON_MATH_LIB_GLSL
+#define COMMON_MATH_LIB_GLSL
+
 /* ---------------------------------------------------------------------- */
 /** \name Common Math Utilities
  * \{ */
@@ -276,3 +280,5 @@ vec3 hue_gradient(float t)
   vec3 p = abs(fract(t + vec3(1.0, 2.0 / 3.0, 1.0 / 3.0)) * 6.0 - 3.0);
   return (clamp(p - 1.0, 0.0, 1.0));
 }
+
+#endif /* COMMON_MATH_LIB_GLSL */
diff --git a/source/blender/draw/intern/shaders/common_view_lib.glsl b/source/blender/draw/intern/shaders/common_view_lib.glsl
index a2b8cb4bbd6..4086162a530 100644
--- a/source/blender/draw/intern/shaders/common_view_lib.glsl
+++ b/source/blender/draw/intern/shaders/common_view_lib.glsl
@@ -1,5 +1,10 @@
+
+/* WORKAROUND: to guard against double include in EEVEE. */
+#ifndef COMMON_VIEW_LIB_GLSL
+#define COMMON_VIEW_LIB_GLSL
+
 /* Temporary until we fully make the switch. */
-#ifndef USE_GPU_SHADER_CREATE_INFO
+#if !defined(USE_GPU_SHADER_CREATE_INFO)
 
 #  define DRW_RESOURCE_CHUNK_LEN 512
 
@@ -37,7 +42,10 @@ layout(std140) uniform viewBlock
 
 #define cameraForward ViewMatrixInverse[2].xyz
 #define cameraPos ViewMatrixInverse[3].xyz
-#define cameraVec(P) ((ProjectionMatrix[3][3] == 0.0) ? normalize(cameraPos - P) : cameraForward)
+vec3 cameraVec(vec3 P)
+{
+  return ((ProjectionMatrix[3][3] == 0.0) ? normalize(cameraPos - P) : cameraForward);
+}
 #define viewCameraVec(vP) ((ProjectionMatrix[3][3] == 0.0) ? normalize(-vP) : vec3(0.0, 0.0, 1.0))
 
 #ifdef world_clip_planes_calc_clip_distance
@@ -92,14 +100,14 @@ vec4 pack_line_data(vec2 frag_co, vec2 edge_start, vec2 edge_pos)
 }
 
 /* Temporary until we fully make the switch. */
-#ifndef DRW_SHADER_SHARED_H
+#ifndef USE_GPU_SHADER_CREATE_INFO
 uniform int drw_resourceChunk;
-#endif /* DRW_SHADER_SHARED_H */
+#endif /* USE_GPU_SHADER_CREATE_INFO */
 
 #ifdef GPU_VERTEX_SHADER
 
 /* Temporary until we fully make the switch. */
-#  ifndef DRW_SHADER_SHARED_H
+#  ifndef USE_GPU_SHADER_CREATE_INFO
 
 /* clang-format off */
 #    if defined(IN_PLACE_INSTANCES) || defined(INSTANCED_ATTR) || defined(DRW_LEGACY_MODEL_MATRIX) || defined(GPU_DEPRECATED_AMD_DRIVER)
@@ -121,7 +129,10 @@ uniform int drw_ResourceID;
 
 /* Use this to declare and pass the value if
  * the fragment shader uses the resource_id. */
-#    ifdef USE_GEOMETRY_SHADER
+#    if defined(EEVEE_GENERATED_INTERFACE)
+#      define RESOURCE_ID_VARYING
+#      define PASS_RESOURCE_ID resourceIDFrag = resource_id;
+#    elif defined(USE_GEOMETRY_SHADER)
 #      define RESOURCE_ID_VARYING flat out int resourceIDGeom;
 #      define PASS_RESOURCE_ID resourceIDGeom = resource_id;
 #    else
@@ -129,12 +140,12 @@ uniform int drw_ResourceID;
 #      define PASS_RESOURCE_ID resourceIDFrag = resource_id;
 #    endif
 
-#  endif /* DRW_SHADER_SHARED_H */
+#  endif /* USE_GPU_SHADER_CREATE_INFO */
 
 #endif /* GPU_VERTEX_SHADER */
 
 /* Temporary until we fully make the switch. */
-#ifdef DRW_SHADER_SHARED_H
+#ifdef USE_GPU_SHADER_CREATE_INFO
 /* TODO(fclem): Rename PASS_RESOURCE_ID to DRW_RESOURCE_ID_VARYING_SET */
 #  if defined(UNIFORM_RESOURCE_ID)
 #    define resource_id drw_ResourceID
@@ -159,16 +170,23 @@ uniform int drw_ResourceID;
 /* If used in a fragment / geometry shader, we pass
  * resource_id as varying. */
 #  ifdef GPU_GEOMETRY_SHADER
-#    define RESOURCE_ID_VARYING \
-      flat out int resourceIDFrag; \
-      flat in int resourceIDGeom[];
+/* TODO(fclem): Remove. This is getting ridiculous. */
+#    if !defined(EEVEE_GENERATED_INTERFACE)
+#      define RESOURCE_ID_VARYING \
+        flat out int resourceIDFrag; \
+        flat in int resourceIDGeom[];
+#    else
+#      define RESOURCE_ID_VARYING
+#    endif
 
 #    define resource_id resourceIDGeom
 #    define PASS_RESOURCE_ID resourceIDFrag = resource_id[0];
 #  endif
 
-#  ifdef GPU_FRAGMENT_SHADER
+#  if defined(GPU_FRAGMENT_SHADER)
+#    if !defined(EEVEE_GENERATED_INTERFACE)
 flat in int resourceIDFrag;
+#    endif
 #    define resource_id resourceIDFrag
 #  endif
 #endif
@@ -185,7 +203,9 @@ struct ObjectMatrices {
   mat4 drw_modelMatrix;
   mat4 drw_modelMatrixInverse;
 };
+#  endif /* DRW_SHADER_SHARED_H */
 
+#  ifndef USE_GPU_SHADER_CREATE_INFO
 layout(std140) uniform modelBlock
 {
   ObjectMatrices drw_matrices[DRW_RESOURCE_CHUNK_LEN];
@@ -193,24 +213,24 @@ layout(std140) uniform modelBlock
 
 #    define ModelMatrix (drw_matrices[resource_id].drw_modelMatrix)
 #    define ModelMatrixInverse (drw_matrices[resource_id].drw_modelMatrixInverse)
-#  endif /* DRW_SHADER_SHARED_H */
+#  endif /* USE_GPU_SHADER_CREATE_INFO */
 
 #else /* GPU_INTEL */
 
 /* Temporary until we fully make the switch. */
-#  ifndef DRW_SHADER_SHARED_H
+#  ifndef USE_GPU_SHADER_CREATE_INFO
 /* Intel GPU seems to suffer performance impact when the model matrix is in UBO storage.
  * So for now we just force using the legacy path. */
 /* Note that this is also a workaround of a problem on osx (amd or nvidia)
  * and older amd driver on windows. */
 uniform mat4 ModelMatrix;
 uniform mat4 ModelMatrixInverse;
-#  endif /* DRW_SHADER_SHARED_H */
+#  endif /* USE_GPU_SHADER_CREATE_INFO */
 
 #endif
 
 /* Temporary until we fully make the switch. */
-#ifndef DRW_SHADER_SHARED_H
+#ifndef USE_GPU_SHADER_CREATE_INFO
 #  define resource_handle (drw_resourceChunk * DRW_RESOURCE_CHUNK_LEN + resource_id)
 #endif
 
@@ -337,3 +357,5 @@ vec3 get_view_vector_from_screen_uv(vec2 uv)
     return vec3(0.0, 0.0, 1.0);
   }
 }
+
+#endif /* COMMON_VIEW_LIB_GLSL */