View3D Grid: fix imperial grid drawing

This is a step to finish the D4325 and fix the T61286.
Currently the grid is highlighted in steps of 10 out of 10, which is wrong for the imperial units as seen in `buImperialLenDef`.
The idea of the code is to pass the steps of the grid already dimensioned as a uniform.

Another important thing to note is that subdivisions now only affect the grid without unity.
This matches the 2.7x Blender versions.

No performance loss (almost no gain too).

Reviewers: fclem

Subscribers: zlsa, rl.amorato

Differential Revision: https://developer.blender.org/D4379

1 files changed, 8 insertions, 34 deletions

diff --git a/source/blender/draw/modes/object_mode.c b/source/blender/draw/modes/object_mode.c
index 87fc74f1f72..06e5b521514 100644
--- a/source/blender/draw/modes/object_mode.c
+++ b/source/blender/draw/modes/object_mode.c
@@ -332,7 +332,7 @@ static struct {
 
   OBJECT_Shaders sh_data[GPU_SHADER_CFG_LEN];
 
-  float grid_settings[5];
+  float grid_distance;
   float grid_mesh_size;
   int grid_flag;
   float grid_axes[3];
@@ -340,6 +340,7 @@ static struct {
   int zneg_flag;
   float zplane_axes[3];
   float inv_viewport_size[2];
+  float grid_steps[8];
   bool draw_grid;
   /* Temp buffer textures */
   struct GPUTexture *outlines_depth_tx;
@@ -559,8 +560,6 @@ static void OBJECT_engine_init(void *vedata)
     View3D *v3d = draw_ctx->v3d;
     Scene *scene = draw_ctx->scene;
     RegionView3D *rv3d = draw_ctx->rv3d;
-    float grid_scale = ED_view3d_grid_scale(scene, v3d, NULL);
-    float grid_res;
 
     const bool show_axis_x = (v3d->gridflag & V3D_SHOW_X) != 0;
     const bool show_axis_y = (v3d->gridflag & V3D_SHOW_Y) != 0;
@@ -576,21 +575,6 @@ static void OBJECT_engine_init(void *vedata)
 
     /* if perps */
     if (winmat[3][3] == 0.0f) {
-      float fov;
-      float viewvecs[2][4] = {
-          {1.0f, -1.0f, -1.0f, 1.0f},
-          {-1.0f, 1.0f, -1.0f, 1.0f},
-      };
-
-      /* convert the view vectors to view space */
-      for (int i = 0; i < 2; i++) {
-        mul_m4_v4(wininv, viewvecs[i]);
-        mul_v3_fl(viewvecs[i], 1.0f / viewvecs[i][2]); /* perspective divide */
-      }
-
-      fov = angle_v3v3(viewvecs[0], viewvecs[1]) / 2.0f;
-      grid_res = fabsf(tanf(fov)) / grid_scale;
-
       e_data.grid_flag = (1 << 4); /* XY plane */
       if (show_axis_x) {
         e_data.grid_flag |= SHOW_AXIS_X;
@@ -603,14 +587,6 @@ static void OBJECT_engine_init(void *vedata)
       }
     }
     else {
-      if (rv3d->view != RV3D_VIEW_USER) {
-        /* Allow 3 more subdivisions. */
-        grid_scale /= powf(v3d->gridsubdiv, 3);
-      }
-
-      float viewdist = 1.0f / max_ff(fabsf(winmat[0][0]), fabsf(winmat[1][1]));
-      grid_res = viewdist / grid_scale;
-
       if (ELEM(rv3d->view, RV3D_VIEW_RIGHT, RV3D_VIEW_LEFT)) {
         e_data.draw_grid = show_ortho_grid;
         e_data.grid_flag = PLANE_YZ | SHOW_AXIS_Y | SHOW_AXIS_Z | SHOW_GRID | GRID_BACK;
@@ -688,12 +664,7 @@ static void OBJECT_engine_init(void *vedata)
       dist = v3d->clip_end;
     }
 
-    e_data.grid_settings[0] = dist / 2.0f;     /* gridDistance */
-    e_data.grid_settings[1] = grid_res;        /* gridResolution */
-    e_data.grid_settings[2] = grid_scale;      /* gridScale */
-    e_data.grid_settings[3] = v3d->gridsubdiv; /* gridSubdiv */
-    e_data.grid_settings[4] = (v3d->gridsubdiv > 1) ? 1.0f / logf(v3d->gridsubdiv) :
-                                                      0.0f; /* 1/log(gridSubdiv) */
+    e_data.grid_distance = dist / 2.0f; /* gridDistance */
 
     if (winmat[3][3] == 0.0f) {
       e_data.grid_mesh_size = dist;
@@ -702,6 +673,8 @@ static void OBJECT_engine_init(void *vedata)
       float viewdist = 1.0f / min_ff(fabsf(winmat[0][0]), fabsf(winmat[1][1]));
       e_data.grid_mesh_size = viewdist * dist;
     }
+
+    ED_view3d_grid_steps(scene, v3d, rv3d, e_data.grid_steps);
   }
 
   copy_v2_v2(e_data.inv_viewport_size, DRW_viewport_size_get());
@@ -1512,10 +1485,10 @@ static void OBJECT_cache_init(void *vedata)
     DRWShadingGroup *grp = DRW_shgroup_create(sh_data->grid, psl->grid);
     DRW_shgroup_uniform_int(grp, "gridFlag", &e_data.zneg_flag, 1);
     DRW_shgroup_uniform_vec3(grp, "planeAxes", e_data.zplane_axes, 1);
-    DRW_shgroup_uniform_vec4(grp, "gridSettings", e_data.grid_settings, 1);
+    DRW_shgroup_uniform_vec3(grp, "screenVecs[0]", DRW_viewport_screenvecs_get(), 2);
+    DRW_shgroup_uniform_float(grp, "gridDistance", &e_data.grid_distance, 1);
     DRW_shgroup_uniform_float_copy(grp, "lineKernel", grid_line_size);
     DRW_shgroup_uniform_float_copy(grp, "meshSize", e_data.grid_mesh_size);
-    DRW_shgroup_uniform_float(grp, "gridOneOverLogSubdiv", &e_data.grid_settings[4], 1);
     DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
     DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
     DRW_shgroup_call(grp, geom, NULL);
@@ -1525,6 +1498,7 @@ static void OBJECT_cache_init(void *vedata)
     DRW_shgroup_uniform_vec3(grp, "planeAxes", e_data.grid_axes, 1);
     DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
     DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth);
+    DRW_shgroup_uniform_float(grp, "gridSteps", e_data.grid_steps, ARRAY_SIZE(e_data.grid_steps));
     DRW_shgroup_call(grp, geom, NULL);
 
     grp = DRW_shgroup_create(sh_data->grid, psl->grid);