Cleanup: Grease Pencil: Remove uneeded push-constants

All of these push-constants were either redundant or
not used anymore.

Pull Request: https://projects.blender.org/blender/blender/pulls/135561

source/blender/draw/engines/gpencil/gpencil_cache_utils.cc

@@ -50,7 +50,6 @@ GPENCIL_tObject *gpencil_object_cache_add(GPENCIL_Instance *inst,
   tgp_ob->vfx.first = tgp_ob->vfx.last = nullptr;
   tgp_ob->camera_z = dot_v3v3(inst->camera_z_axis, ob->object_to_world().location());
   tgp_ob->is_drawmode3d = is_stroke_order_3d;
-  tgp_ob->object_scale = mat4_to_scale(ob->object_to_world().ptr());
 
   /* Check if any material with holdout flag enabled. */
   tgp_ob->do_mat_holdout = false;
@@ -317,9 +316,6 @@ GPENCIL_tLayer *grease_pencil_layer_cache_add(GPENCIL_Instance *inst,
   const float vert_col_opacity = (override_vertcol) ?
                                      (is_vert_col_mode ? inst->vertex_paint_opacity : 0.0f) :
                                      (inst->is_render ? 1.0f : inst->vertex_paint_opacity);
-  /* Negate thickness sign to tag that strokes are in screen space (this is no longer used in
-   * GPv3). Convert to world units (by default, 1 meter = 1000 pixels). */
-  const float thickness_scale = blender::bke::greasepencil::LEGACY_RADIUS_CONVERSION_FACTOR;
   /* If the layer is used as a mask (but is otherwise not visible in the render), render it with a
    * opacity of 0 so that it can still mask other layers. */
   const float layer_opacity = !is_used_as_mask ? grease_pencil_layer_final_opacity_get(
@@ -454,10 +450,6 @@ GPENCIL_tLayer *grease_pencil_layer_cache_add(GPENCIL_Instance *inst,
     pass.bind_texture("gpMaskTexture", mask_tex);
     pass.push_constant("gpNormal", tgp_ob->plane_normal);
     pass.push_constant("gpStrokeOrder3d", tgp_ob->is_drawmode3d);
-    pass.push_constant("gpThicknessScale", tgp_ob->object_scale);
-    /* Replaced by a modifier in GPv3. */
-    pass.push_constant("gpThicknessOffset", 0.0f);
-    pass.push_constant("gpThicknessWorldScale", thickness_scale);
     pass.push_constant("gpVertexColorOpacity", vert_col_opacity);
 
     pass.bind_texture("gpFillTexture", inst->dummy_tx);

source/blender/draw/engines/gpencil/gpencil_engine.h

@@ -136,8 +136,6 @@ typedef struct GPENCIL_tObject {
 
   /* Distance to camera. Used for sorting. */
   float camera_z;
-  /* Used for stroke thickness scaling. */
-  float object_scale;
   /* Normal used for shading. Based on view angle. */
   float3 plane_normal;
   /* Used for drawing depth merge pass. */

source/blender/draw/engines/overlay/overlay_next_grease_pencil.hh

@@ -310,16 +310,10 @@ class GreasePencil : Overlay {
     const Vector<DrawingInfo> drawings = retrieve_visible_drawings(*scene, grease_pencil, true);
     for (const DrawingInfo info : drawings) {
 
-      const float object_scale = mat4_to_scale(ob->object_to_world().ptr());
-      const float thickness_scale = bke::greasepencil::LEGACY_RADIUS_CONVERSION_FACTOR;
-
       gpu::VertBuf *position_tx = draw::DRW_cache_grease_pencil_position_buffer_get(scene, ob);
       gpu::VertBuf *color_tx = draw::DRW_cache_grease_pencil_color_buffer_get(scene, ob);
 
       pass.push_constant("gpStrokeOrder3d", is_stroke_order_3d);
-      pass.push_constant("gpThicknessScale", object_scale);
-      pass.push_constant("gpThicknessOffset", 0.0f);
-      pass.push_constant("gpThicknessWorldScale", thickness_scale);
       pass.bind_texture("gp_pos_tx", position_tx);
       pass.bind_texture("gp_col_tx", color_tx);
 

source/blender/draw/intern/draw_cache_impl_grease_pencil.cc

@@ -1212,9 +1212,6 @@ static void grease_pencil_geom_batch_ensure(Object &object,
        * use negative values as a special 'flag' to get rounded caps. */
       s_vert.radius = math::max(radii[point_i], 0.0f) *
                       ((end_cap == GP_STROKE_CAP_TYPE_ROUND) ? 1.0f : -1.0f);
-      /* Convert to legacy "pixel" space. We divide here, because the shader expects the values to
-       * be in the `px` space rather than world space. Otherwise the values will get clamped. */
-      s_vert.radius /= bke::greasepencil::LEGACY_RADIUS_CONVERSION_FACTOR;
       s_vert.opacity = opacities[point_i] *
                        ((start_cap == GP_STROKE_CAP_TYPE_ROUND) ? 1.0f : -1.0f);
       s_vert.point_id = verts_range[idx];

source/blender/draw/intern/shaders/draw_grease_pencil_lib.glsl

@@ -75,18 +75,20 @@ vec2 gpencil_project_to_screenspace(vec4 v, vec4 viewport_size)
 
 float gpencil_stroke_thickness_modulate(float thickness, vec4 ndc_pos, vec4 viewport_size)
 {
-  /* Modify stroke thickness by object and layer factors. */
-  thickness = max(1.0, thickness * gpThicknessScale + gpThicknessOffset);
+  /* Modify stroke thickness by object scale. */
+  thickness = length(to_float3x3(drw_modelmat()) * vec3(thickness * M_SQRT1_3));
+
+  /* For compatibility, thickness has to be clamped after being multiplied by this factor.
+   * This clamping was introduced to reduce aliasing issue by instead fading the lines alpha at
+   * smaller radii. This can be removed in major release if compatibility is not a concern. */
+  const float legacy_radius_conversion_factor = 2000.0;
+  thickness *= legacy_radius_conversion_factor;
+  thickness = max(1.0, thickness);
+  thickness /= legacy_radius_conversion_factor;
+
+  /* World space point size. */
+  thickness *= drw_view().winmat[1][1] * viewport_size.y;
 
-  if (gpThicknessIsScreenSpace) {
-    /* Multiply offset by view Z so that offset is constant in screen-space.
-     * (e.i: does not change with the distance to camera) */
-    thickness *= ndc_pos.w;
-  }
-  else {
-    /* World space point size. */
-    thickness *= gpThicknessWorldScale * drw_view().winmat[1][1] * viewport_size.y;
-  }
   return thickness;
 }
 

source/blender/draw/intern/shaders/draw_object_infos_info.hh

@@ -103,12 +103,6 @@ TYPEDEF_SOURCE("gpencil_shader_shared.h")
 DEFINE("DRW_GPENCIL_INFO")
 SAMPLER(0, FLOAT_BUFFER, gp_pos_tx)
 SAMPLER(1, FLOAT_BUFFER, gp_col_tx)
-/* Per Object */
-PUSH_CONSTANT(FLOAT, gpThicknessScale)      /* TODO(fclem): Replace with object info. */
-PUSH_CONSTANT(FLOAT, gpThicknessWorldScale) /* TODO(fclem): Same as above. */
-DEFINE_VALUE("gpThicknessIsScreenSpace", "(gpThicknessWorldScale < 0.0)")
-/* Per Layer */
-PUSH_CONSTANT(FLOAT, gpThicknessOffset)
 ADDITIONAL_INFO(draw_resource_id_varying)
 ADDITIONAL_INFO(draw_view)
 ADDITIONAL_INFO(draw_object_infos)

source/blender/draw/intern/shaders/draw_view_info.hh

@@ -18,7 +18,6 @@
 #  define USE_WORLD_CLIP_PLANES
 
 #  define DRW_VIEW_LEN DRW_VIEW_MAX
-#  define gpThicknessIsScreenSpace (gpThicknessWorldScale < 0.0)
 #endif
 
 #include "gpu_shader_create_info.hh"