Metal: GPU_PRIM_LINE_LOOP alternative implementations.

Prefer using immVertex3f when 3D shaders are used for 2D rendering due to overhead of vertex padding in hardware. CPU overhead is negligible.

Authored by Apple: Michael Parkin-White

Ref T96261

Reviewed By: fclem

Maniphest Tasks: T96261

Differential Revision: https://developer.blender.org/D14494

5 files changed, 131 insertions, 64 deletions

diff --git a/source/blender/editors/gizmo_library/gizmo_draw_utils.c b/source/blender/editors/gizmo_library/gizmo_draw_utils.c
index 8d2aec18451..c6303c197e7 100644
--- a/source/blender/editors/gizmo_library/gizmo_draw_utils.c
+++ b/source/blender/editors/gizmo_library/gizmo_draw_utils.c
@@ -82,9 +82,35 @@ void wm_gizmo_vec_draw(
     const float color[4], const float (*verts)[3], uint vert_count, uint pos, uint primitive_type)
 {
   immUniformColor4fv(color);
-  immBegin(primitive_type, vert_count);
-  for (int i = 0; i < vert_count; i++) {
-    immVertex3fv(pos, verts[i]);
+
+  if (primitive_type == GPU_PRIM_LINE_LOOP) {
+    /* Line loop alternative for Metal/Vulkan. */
+    immBegin(GPU_PRIM_LINES, vert_count * 2);
+    immVertex3fv(pos, verts[0]);
+    for (int i = 1; i < vert_count; i++) {
+      immVertex3fv(pos, verts[i]);
+      immVertex3fv(pos, verts[i]);
+    }
+    immVertex3fv(pos, verts[0]);
+    immEnd();
+  }
+  else if (primitive_type == GPU_PRIM_TRI_FAN) {
+    /* Note(Metal): Tri-fan alternative for Metal. Triangle List is more efficient for small
+     * primitive counts. */
+    int tri_count = vert_count - 2;
+    immBegin(GPU_PRIM_TRIS, tri_count * 3);
+    for (int i = 0; i < tri_count; i++) {
+      immVertex3fv(pos, verts[0]);
+      immVertex3fv(pos, verts[i + 1]);
+      immVertex3fv(pos, verts[i + 2]);
+    }
+    immEnd();
+  }
+  else {
+    immBegin(primitive_type, vert_count);
+    for (int i = 0; i < vert_count; i++) {
+      immVertex3fv(pos, verts[i]);
+    }
+    immEnd();
   }
-  immEnd();
 }
diff --git a/source/blender/editors/gizmo_library/gizmo_types/button2d_gizmo.c b/source/blender/editors/gizmo_library/gizmo_types/button2d_gizmo.c
index 5e20cc73f1a..b326d6d1859 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/button2d_gizmo.c
+++ b/source/blender/editors/gizmo_library/gizmo_types/button2d_gizmo.c
@@ -74,20 +74,21 @@ static void button2d_geom_draw_backdrop(const wmGizmo *gz,
   GPU_viewport_size_get_f(viewport);
 
   GPUVertFormat *format = immVertexFormat();
-  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  /* Note(Metal): Prefer 3D coordinate for 2D rendering when using 3D shader. */
+  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
   /* TODO: other draw styles. */
   if (color[3] == 1.0 && fill_alpha == 1.0 && select == false) {
     immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
     immUniformColor4fv(color);
-    imm_draw_circle_fill_2d(pos, 0, 0, 1.0f, CIRCLE_RESOLUTION);
+    imm_draw_circle_fill_3d(pos, 0.0f, 0.0f, 1.0f, CIRCLE_RESOLUTION);
     immUnbindProgram();
 
     immBindBuiltinProgram(GPU_SHADER_3D_POLYLINE_UNIFORM_COLOR);
     immUniform2fv("viewportSize", &viewport[2]);
     immUniform1f("lineWidth", gz->line_width * U.pixelsize);
     immUniformColor4fv(color);
-    imm_draw_circle_wire_2d(pos, 0, 0, 1.0f, CIRCLE_RESOLUTION);
+    imm_draw_circle_wire_3d(pos, 0.0f, 0.0f, 1.0f, CIRCLE_RESOLUTION);
     immUnbindProgram();
   }
   else {
@@ -96,7 +97,7 @@ static void button2d_geom_draw_backdrop(const wmGizmo *gz,
       const float fill_color[4] = {UNPACK3(color), fill_alpha * color[3]};
       immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
       immUniformColor4fv(fill_color);
-      imm_draw_circle_fill_2d(pos, 0, 0, 1.0f, CIRCLE_RESOLUTION);
+      imm_draw_circle_fill_3d(pos, 0.0f, 0.0f, 1.0f, CIRCLE_RESOLUTION);
       immUnbindProgram();
     }
 
@@ -106,7 +107,7 @@ static void button2d_geom_draw_backdrop(const wmGizmo *gz,
       immUniform2fv("viewportSize", &viewport[2]);
       immUniform1f("lineWidth", gz->line_width * U.pixelsize);
       immUniformColor4fv(color);
-      imm_draw_circle_wire_2d(pos, 0, 0, 1.0f, CIRCLE_RESOLUTION);
+      imm_draw_circle_wire_3d(pos, 0.0f, 0.0f, 1.0f, CIRCLE_RESOLUTION);
       immUnbindProgram();
     }
   }
diff --git a/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.c b/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.c
index 4c54aa10c33..e4cb6d149f5 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.c
+++ b/source/blender/editors/gizmo_library/gizmo_types/cage2d_gizmo.c
@@ -99,7 +99,8 @@ static void cage2d_draw_box_corners(const rctf *r,
                                     const float color[3],
                                     const float line_width)
 {
-  uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  /* Note(Metal): Prefer using 3D coordinates with 3D shader, even if rendering 2D gizmo's. */
+  uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
   immBindBuiltinProgram(GPU_SHADER_3D_POLYLINE_UNIFORM_COLOR);
   immUniformColor3fv(color);
@@ -112,25 +113,25 @@ static void cage2d_draw_box_corners(const rctf *r,
 
   immBegin(GPU_PRIM_LINES, 16);
 
-  immVertex2f(pos, r->xmin, r->ymin + margin[1]);
-  immVertex2f(pos, r->xmin, r->ymin);
-  immVertex2f(pos, r->xmin, r->ymin);
-  immVertex2f(pos, r->xmin + margin[0], r->ymin);
+  immVertex3f(pos, r->xmin, r->ymin + margin[1], 0.0f);
+  immVertex3f(pos, r->xmin, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmin, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmin + margin[0], r->ymin, 0.0f);
 
-  immVertex2f(pos, r->xmax, r->ymin + margin[1]);
-  immVertex2f(pos, r->xmax, r->ymin);
-  immVertex2f(pos, r->xmax, r->ymin);
-  immVertex2f(pos, r->xmax - margin[0], r->ymin);
+  immVertex3f(pos, r->xmax, r->ymin + margin[1], 0.0f);
+  immVertex3f(pos, r->xmax, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmax, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmax - margin[0], r->ymin, 0.0f);
 
-  immVertex2f(pos, r->xmax, r->ymax - margin[1]);
-  immVertex2f(pos, r->xmax, r->ymax);
-  immVertex2f(pos, r->xmax, r->ymax);
-  immVertex2f(pos, r->xmax - margin[0], r->ymax);
+  immVertex3f(pos, r->xmax, r->ymax - margin[1], 0.0f);
+  immVertex3f(pos, r->xmax, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmax, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmax - margin[0], r->ymax, 0.0f);
 
-  immVertex2f(pos, r->xmin, r->ymax - margin[1]);
-  immVertex2f(pos, r->xmin, r->ymax);
-  immVertex2f(pos, r->xmin, r->ymax);
-  immVertex2f(pos, r->xmin + margin[0], r->ymax);
+  immVertex3f(pos, r->xmin, r->ymax - margin[1], 0.0f);
+  immVertex3f(pos, r->xmin, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmin, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmin + margin[0], r->ymax, 0.0f);
 
   immEnd();
 
@@ -440,12 +441,35 @@ static void cage2d_draw_box_interaction(const float color[4],
 static void imm_draw_point_aspect_2d(
     uint pos, float x, float y, float rad_x, float rad_y, bool solid)
 {
-  immBegin(solid ? GPU_PRIM_TRI_FAN : GPU_PRIM_LINE_LOOP, 4);
-  immVertex2f(pos, x - rad_x, y - rad_y);
-  immVertex2f(pos, x - rad_x, y + rad_y);
-  immVertex2f(pos, x + rad_x, y + rad_y);
-  immVertex2f(pos, x + rad_x, y - rad_y);
-  immEnd();
+  if (solid) {
+    /* Note(Metal/AMD): Small Triangle-list primitives more optimal for GPU HW than Trianglestrip.
+     */
+    immBegin(GPU_PRIM_TRIS, 6);
+    immVertex2f(pos, x - rad_x, y - rad_y);
+    immVertex2f(pos, x - rad_x, y + rad_y);
+    immVertex2f(pos, x + rad_x, y + rad_y);
+
+    immVertex2f(pos, x - rad_x, y - rad_y);
+    immVertex2f(pos, x + rad_x, y + rad_y);
+    immVertex2f(pos, x + rad_x, y - rad_y);
+    immEnd();
+  }
+  else {
+    /* Note(Metal/AMD): Small Line-list primitives more optimal for GPU HW than Linestrip. */
+    immBegin(GPU_PRIM_LINES, 8);
+    immVertex2f(pos, x - rad_x, y - rad_y);
+    immVertex2f(pos, x - rad_x, y + rad_y);
+
+    immVertex2f(pos, x - rad_x, y + rad_y);
+    immVertex2f(pos, x + rad_x, y + rad_y);
+
+    immVertex2f(pos, x + rad_x, y + rad_y);
+    immVertex2f(pos, x + rad_x, y - rad_y);
+
+    immVertex2f(pos, x + rad_x, y - rad_y);
+    immVertex2f(pos, x - rad_x, y - rad_y);
+    immEnd();
+  }
 }
 
 static void cage2d_draw_circle_wire(const rctf *r,
@@ -455,7 +479,9 @@ static void cage2d_draw_circle_wire(const rctf *r,
                                     const int draw_options,
                                     const float line_width)
 {
-  uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  /* Note(Metal): Prefer using 3D coordinates with 3D shader input, even if rendering 2D gizmo's.
+   */
+  uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
   immBindBuiltinProgram(GPU_SHADER_3D_POLYLINE_UNIFORM_COLOR);
   immUniformColor3fv(color);
@@ -465,17 +491,28 @@ static void cage2d_draw_circle_wire(const rctf *r,
   immUniform2fv("viewportSize", &viewport[2]);
   immUniform1f("lineWidth", line_width * U.pixelsize);
 
-  immBegin(GPU_PRIM_LINE_LOOP, 4);
-  immVertex2f(pos, r->xmin, r->ymin);
-  immVertex2f(pos, r->xmax, r->ymin);
-  immVertex2f(pos, r->xmax, r->ymax);
-  immVertex2f(pos, r->xmin, r->ymax);
+  /* Small 'lines' primitives more efficient for hardware processing than linestrip. */
+  immBegin(GPU_PRIM_LINES, 8);
+  immVertex3f(pos, r->xmin, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmax, r->ymin, 0.0f);
+
+  immVertex3f(pos, r->xmax, r->ymin, 0.0f);
+  immVertex3f(pos, r->xmax, r->ymax, 0.0f);
+
+  immVertex3f(pos, r->xmax, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmin, r->ymax, 0.0f);
+
+  immVertex3f(pos, r->xmin, r->ymax, 0.0f);
+  immVertex3f(pos, r->xmin, r->ymin, 0.0f);
   immEnd();
 
   if (transform_flag & ED_GIZMO_CAGE2D_XFORM_FLAG_ROTATE) {
-    immBegin(GPU_PRIM_LINE_LOOP, 2);
-    immVertex2f(pos, BLI_rctf_cent_x(r), r->ymax);
-    immVertex2f(pos, BLI_rctf_cent_x(r), r->ymax + margin[1]);
+    immBegin(GPU_PRIM_LINES, 4);
+    immVertex3f(pos, BLI_rctf_cent_x(r), r->ymax, 0.0f);
+    immVertex3f(pos, BLI_rctf_cent_x(r), r->ymax + margin[1], 0.0f);
+
+    immVertex3f(pos, BLI_rctf_cent_x(r), r->ymax + margin[1], 0.0f);
+    immVertex3f(pos, BLI_rctf_cent_x(r), r->ymax, 0.0f);
     immEnd();
   }
 
@@ -485,10 +522,10 @@ static void cage2d_draw_circle_wire(const rctf *r,
       const float center[2] = {BLI_rctf_cent_x(r), BLI_rctf_cent_y(r)};
 
       immBegin(GPU_PRIM_LINES, 4);
-      immVertex2f(pos, center[0] - rad[0], center[1] - rad[1]);
-      immVertex2f(pos, center[0] + rad[0], center[1] + rad[1]);
-      immVertex2f(pos, center[0] + rad[0], center[1] - rad[1]);
-      immVertex2f(pos, center[0] - rad[0], center[1] + rad[1]);
+      immVertex3f(pos, center[0] - rad[0], center[1] - rad[1], 0.0f);
+      immVertex3f(pos, center[0] + rad[0], center[1] + rad[1], 0.0f);
+      immVertex3f(pos, center[0] + rad[0], center[1] - rad[1], 0.0f);
+      immVertex3f(pos, center[0] - rad[0], center[1] + rad[1], 0.0f);
       immEnd();
     }
   }
diff --git a/source/blender/editors/gizmo_library/gizmo_types/dial3d_gizmo.c b/source/blender/editors/gizmo_library/gizmo_types/dial3d_gizmo.c
index e1f584bf9e4..a76242404ba 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/dial3d_gizmo.c
+++ b/source/blender/editors/gizmo_library/gizmo_types/dial3d_gizmo.c
@@ -96,7 +96,8 @@ static void dial_geom_draw(const float color[4],
                                                  ED_GIZMO_DIAL_DRAW_FLAG_FILL)));
 
   GPUVertFormat *format = immVertexFormat();
-  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  /* Note(Metal): Prefer using 3D coordinates with 3D shader, even if rendering 2D gizmo's. */
+  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
   if (clip_plane) {
     immBindBuiltinProgram(filled ? GPU_SHADER_3D_CLIPPED_UNIFORM_COLOR :
@@ -114,18 +115,19 @@ static void dial_geom_draw(const float color[4],
   if (filled) {
     if (arc_partial_angle == 0.0f) {
       if (arc_inner_factor == 0.0f) {
-        imm_draw_circle_fill_2d(pos, 0, 0, 1.0, DIAL_RESOLUTION);
+        imm_draw_circle_fill_3d(pos, 0.0f, 0.0f, 1.0f, DIAL_RESOLUTION);
       }
       else {
-        imm_draw_disk_partial_fill_2d(
-            pos, 0, 0, arc_inner_factor, 1.0f, DIAL_RESOLUTION, 0, RAD2DEGF(M_PI * 2));
+        imm_draw_disk_partial_fill_3d(
+            pos, 0.0f, 0.0f, 0.0f, arc_inner_factor, 1.0f, DIAL_RESOLUTION, 0, RAD2DEGF(M_PI * 2));
       }
     }
     else {
       float arc_partial_deg = RAD2DEGF((M_PI * 2) - arc_partial_angle);
-      imm_draw_disk_partial_fill_2d(pos,
-                                    0,
-                                    0,
+      imm_draw_disk_partial_fill_3d(pos,
+                                    0.0f,
+                                    0.0f,
+                                    0.0f,
                                     arc_inner_factor,
                                     1.0f,
                                     DIAL_RESOLUTION,
@@ -140,15 +142,15 @@ static void dial_geom_draw(const float color[4],
     immUniform1f("lineWidth", line_width * U.pixelsize);
 
     if (arc_partial_angle == 0.0f) {
-      imm_draw_circle_wire_2d(pos, 0, 0, 1.0, DIAL_RESOLUTION);
+      imm_draw_circle_wire_3d(pos, 0.0f, 0.0f, 1.0f, DIAL_RESOLUTION);
       if (arc_inner_factor != 0.0f) {
-        imm_draw_circle_wire_2d(pos, 0, 0, arc_inner_factor, DIAL_RESOLUTION);
+        imm_draw_circle_wire_3d(pos, 0.0f, 0.0f, arc_inner_factor, DIAL_RESOLUTION);
       }
     }
     else {
       float arc_partial_deg = RAD2DEGF((M_PI * 2) - arc_partial_angle);
-      imm_draw_circle_partial_wire_2d(
-          pos, 0, 0, 1.0, DIAL_RESOLUTION, -arc_partial_deg / 2, arc_partial_deg);
+      imm_draw_circle_partial_wire_3d(
+          pos, 0.0f, 0.0f, 0.0f, 1.0f, DIAL_RESOLUTION, -arc_partial_deg / 2, arc_partial_deg);
 #  if 0
       if (arc_inner_factor != 0.0f) {
         BLI_assert(0);
@@ -186,7 +188,7 @@ static void dial_ghostarc_draw_helpline(const float angle,
   immUniformColor4fv(color);
 
   immBegin(GPU_PRIM_LINE_STRIP, 2);
-  immVertex3f(pos, 0.0f, 0, 0.0f);
+  immVertex3f(pos, 0.0f, 0.0f, 0.0f);
   immVertex3fv(pos, co_outer);
   immEnd();
 
diff --git a/source/blender/editors/gizmo_library/gizmo_types/move3d_gizmo.c b/source/blender/editors/gizmo_library/gizmo_types/move3d_gizmo.c
index 447fe1005a1..5fb1173521a 100644
--- a/source/blender/editors/gizmo_library/gizmo_types/move3d_gizmo.c
+++ b/source/blender/editors/gizmo_library/gizmo_types/move3d_gizmo.c
@@ -98,7 +98,8 @@ static void move_geom_draw(const wmGizmo *gz,
                                                  ED_GIZMO_MOVE_DRAW_FLAG_FILL)));
 
   GPUVertFormat *format = immVertexFormat();
-  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
+  /* Note(Metal): Prefer using 3D coordinates with 3D shader, even if rendering 2D gizmo's. */
+  uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
   immBindBuiltinProgram(filled ? GPU_SHADER_3D_UNIFORM_COLOR :
                                  GPU_SHADER_3D_POLYLINE_UNIFORM_COLOR);
@@ -115,20 +116,20 @@ static void move_geom_draw(const wmGizmo *gz,
 
   if (draw_style == ED_GIZMO_MOVE_STYLE_RING_2D) {
     if (filled) {
-      imm_draw_circle_fill_2d(pos, 0, 0, radius, DIAL_RESOLUTION);
+      imm_draw_circle_fill_3d(pos, 0.0f, 0.0f, radius, DIAL_RESOLUTION);
     }
     else {
-      imm_draw_circle_wire_2d(pos, 0, 0, radius, DIAL_RESOLUTION);
+      imm_draw_circle_wire_3d(pos, 0.0f, 0.0f, radius, DIAL_RESOLUTION);
     }
   }
   else if (draw_style == ED_GIZMO_MOVE_STYLE_CROSS_2D) {
     const float radius_diag = M_SQRT1_2 * radius;
     immBegin(GPU_PRIM_LINES, 4);
-    immVertex2f(pos, radius_diag, radius_diag);
-    immVertex2f(pos, -radius_diag, -radius_diag);
+    immVertex3f(pos, radius_diag, radius_diag, 0.0f);
+    immVertex3f(pos, -radius_diag, -radius_diag, 0.0f);
 
-    immVertex2f(pos, -radius_diag, radius_diag);
-    immVertex2f(pos, radius_diag, -radius_diag);
+    immVertex3f(pos, -radius_diag, radius_diag, 0.0f);
+    immVertex3f(pos, radius_diag, -radius_diag, 0.0f);
     immEnd();
   }
   else {