Overlay Engine: Make thickwires (linesize > 1.0) using the Wire AA pass

This fixes the limitation of OSX not allowing glLineWidth with size > 1.0.
This however only fix the viewport wire drawing.

source/blender/draw/engines/overlay/overlay_antialiasing.c

@@ -80,8 +80,9 @@ void OVERLAY_antialiasing_init(OVERLAY_Data *vedata)
     return;
   }
 
+  bool need_wire_expansion = (G_draw.block.sizePixel > 1.0f);
   /* TODO Get real userpref option and remove MSAA buffer. */
-  pd->antialiasing.enabled = dtxl->multisample_color != NULL;
+  pd->antialiasing.enabled = (dtxl->multisample_color != NULL) || need_wire_expansion;
 
   /* Use default view */
   pd->view_default = (DRWView *)DRW_view_default_get();
@@ -124,11 +125,15 @@ void OVERLAY_antialiasing_cache_init(OVERLAY_Data *vedata)
   DRWShadingGroup *grp;
 
   if (pd->antialiasing.enabled) {
+    /* TODO Get real userpref option and remove MSAA buffer. */
+    const bool do_smooth_lines = (dtxl->multisample_color != NULL);
+
     DRW_PASS_CREATE(psl->antialiasing_ps, DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ALPHA_PREMUL);
 
     sh = OVERLAY_shader_antialiasing();
     grp = DRW_shgroup_create(sh, psl->antialiasing_ps);
     DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
+    DRW_shgroup_uniform_bool_copy(grp, "doSmoothLines", do_smooth_lines);
     DRW_shgroup_uniform_texture_ref(grp, "depthTex", &dtxl->depth);
     DRW_shgroup_uniform_texture_ref(grp, "colorTex", &txl->overlay_color_tx);
     DRW_shgroup_uniform_texture_ref(grp, "lineTex", &txl->overlay_line_tx);

source/blender/draw/engines/overlay/shaders/antialiasing_frag.glsl

@@ -2,6 +2,7 @@
 uniform sampler2D colorTex;
 uniform sampler2D depthTex;
 uniform sampler2D lineTex;
+uniform bool doSmoothLines;
 
 in vec2 uvs;
 
@@ -26,11 +27,23 @@ out vec4 fragColor;
  */
 float line_coverage(float distance_to_line, float line_kernel_size)
 {
-  return smoothstep(LINE_SMOOTH_END, LINE_SMOOTH_START, abs(distance_to_line) - line_kernel_size);
+  if (doSmoothLines) {
+    return smoothstep(
+        LINE_SMOOTH_END, LINE_SMOOTH_START, abs(distance_to_line) - line_kernel_size);
+  }
+  else {
+    return step(-0.5, line_kernel_size - abs(distance_to_line));
+  }
 }
 vec4 line_coverage(vec4 distance_to_line, float line_kernel_size)
 {
-  return smoothstep(LINE_SMOOTH_END, LINE_SMOOTH_START, abs(distance_to_line) - line_kernel_size);
+  if (doSmoothLines) {
+    return smoothstep(
+        LINE_SMOOTH_END, LINE_SMOOTH_START, abs(distance_to_line) - line_kernel_size);
+  }
+  else {
+    return step(-0.5, line_kernel_size - abs(distance_to_line));
+  }
 }
 
 vec2 decode_line_dir(vec2 dir)
@@ -79,7 +92,7 @@ void neighbor_blend(
 void main()
 {
   ivec2 center_texel = ivec2(gl_FragCoord.xy);
-  const float line_kernel = 0.0;
+  float line_kernel = sizePixel * 0.5 - 0.5;
 
   fragColor = texelFetch(colorTex, center_texel, 0);
 

source/blender/draw/intern/DRW_render.h

@@ -350,7 +350,7 @@ typedef enum {
   DRW_STATE_LOGIC_INVERT = (1 << 26),
   DRW_STATE_SHADOW_OFFSET = (1 << 27),
   DRW_STATE_CLIP_PLANES = (1 << 28),
-  DRW_STATE_WIRE_SMOOTH = (1 << 29),
+  // DRW_STATE_WIRE_SMOOTH = (1 << 29), /* UNUSED */
   DRW_STATE_FIRST_VERTEX_CONVENTION = (1 << 30),
   /** DO NOT USE. Assumed always enabled. Only used internally. */
   DRW_STATE_PROGRAM_POINT_SIZE = (1u << 31),

source/blender/draw/intern/draw_manager_exec.c

@@ -230,21 +230,6 @@ void drw_state_set(DRWState state)
     }
   }
 
-  /* Wire Width */
-  {
-    int test;
-    if ((test = CHANGED_TO(DRW_STATE_WIRE_SMOOTH))) {
-      if (test == 1) {
-        GPU_line_width(2.0f);
-        GPU_line_smooth(true);
-      }
-      else {
-        GPU_line_width(1.0f);
-        GPU_line_smooth(false);
-      }
-    }
-  }
-
   /* Blending (all buffer) */
   {
     int test;
@@ -453,7 +438,11 @@ void DRW_state_reset(void)
 {
   DRW_state_reset_ex(DRW_STATE_DEFAULT);
 
+  /* Should stay constant during the whole rendering. */
   GPU_point_size(5);
+  GPU_line_smooth(false);
+  /* Bypass U.pixelsize factor. */
+  glLineWidth(1.0f);
 
   /* Reset blending function */
   glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);