Fix T64499: edit mode display glitch on Intel HD 4x00 and Windows 7/8

There may well be more vertex shaders that need this, but I couldn't find them
in my testing.

Differential Revision: https://developer.blender.org/D4921

source/blender/draw/modes/shaders/common_view_lib.glsl

@@ -48,3 +48,11 @@ uniform mat4 ModelMatrixInverse;
 #define point_world_to_ndc(p) (ViewProjectionMatrix * vec4(p, 1.0))
 #define point_world_to_object(p) ((ModelMatrixInverse * vec4(p, 1.0)).xyz)
 #define point_world_to_view(p) ((ViewMatrix * vec4(p, 1.0)).xyz)
+
+/* Due to some shader compiler bug, we somewhat need to access gl_VertexID
+ * to make vertex shaders work. even if it's actually dead code. */
+#ifdef GPU_INTEL
+#  define GPU_INTEL_VERTEX_SHADER_WORKAROUND gl_Position.x = float(gl_VertexID);
+#else
+#  define GPU_INTEL_VERTEX_SHADER_WORKAROUND
+#endif

source/blender/draw/modes/shaders/edit_curve_overlay_handle_vert.glsl

@@ -7,6 +7,8 @@ flat out int vertFlag;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 world_pos = point_object_to_world(pos);
   gl_Position = point_world_to_ndc(world_pos);
   vertFlag = data;

source/blender/draw/modes/shaders/edit_curve_overlay_loosevert_vert.glsl

@@ -9,6 +9,8 @@ out vec4 finalColor;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   if ((data & VERT_SELECTED) != 0) {
     if ((data & VERT_ACTIVE) != 0) {
       finalColor = colorEditMeshActive;

source/blender/draw/modes/shaders/edit_curve_overlay_normals_vert.glsl

@@ -9,6 +9,8 @@ in float rad;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 final_pos = pos;
 
   float flip = (gl_InstanceID != 0) ? -1.0 : 1.0;

source/blender/draw/modes/shaders/edit_lattice_overlay_loosevert_vert.glsl

@@ -22,6 +22,8 @@ vec2 proj(vec4 pos)
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   clipCase = 0;
 
   vec3 world_pos = point_object_to_world(pos);

source/blender/draw/modes/shaders/edit_mesh_overlay_facefill_vert.glsl

@@ -8,6 +8,8 @@ flat out vec4 faceColor;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 world_pos = point_object_to_world(pos);
   gl_Position = point_world_to_ndc(world_pos);
 

source/blender/draw/modes/shaders/edit_mesh_overlay_mesh_analysis_vert.glsl

@@ -12,6 +12,8 @@ out vec4 weightColor;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 world_pos = point_object_to_world(pos);
   gl_Position = point_world_to_ndc(world_pos);
   weightColor = vec4(weight_color.rgb, 1.0);

source/blender/draw/modes/shaders/edit_mesh_overlay_vert.glsl

@@ -20,6 +20,8 @@ out int selectOveride;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 world_pos = point_object_to_world(pos);
 
 #if !defined(FACE)

source/blender/draw/modes/shaders/edit_normals_vert.glsl

@@ -21,6 +21,8 @@ flat out vec4 v2;
 
 void main()
 {
+  GPU_INTEL_VERTEX_SHADER_WORKAROUND
+
   vec3 n = normalize(normal_object_to_world(nor));
 
   vec3 world_pos = point_object_to_world(pos);