1 files changed, 87 insertions, 0 deletions
diff --git a/source/blender/draw/engines/overlay/shaders/overlay_motion_path_line_vert.glsl b/source/blender/draw/engines/overlay/shaders/overlay_motion_path_line_vert.glsl
new file mode 100644
index 00000000000..e6281f75b8f
--- /dev/null
+++ b/source/blender/draw/engines/overlay/shaders/overlay_motion_path_line_vert.glsl
@@ -0,0 +1,87 @@
+
+#pragma BLENDER_REQUIRE(common_view_clipping_lib.glsl)
+#pragma BLENDER_REQUIRE(common_view_lib.glsl)
+
+#define frameCurrent mpathLineSettings.x
+#define frameStart mpathLineSettings.y
+#define frameEnd mpathLineSettings.z
+#define cacheStart mpathLineSettings.w
+
+/* project to screen space */
+vec2 proj(vec4 pos)
+{
+  return (0.5 * (pos.xy / pos.w) + 0.5) * sizeViewport.xy;
+}
+
+#define SET_INTENSITY(A, B, C, min, max) \
+  (((1.0 - (float(C - B) / float(C - A))) * (max - min)) + min)
+
+void main()
+{
+  gl_Position = drw_view.persmat * vec4(pos, 1.0);
+
+  interp.ss_pos = proj(gl_Position);
+
+  int frame = gl_VertexID + cacheStart;
+
+  float intensity; /* how faint */
+
+  vec3 blend_base = (abs(frame - frameCurrent) == 0) ?
+                        colorCurrentFrame.rgb :
+                        colorBackground.rgb; /* "bleed" cframe color to ease color blending */
+  bool use_custom_color = customColor.x >= 0.0;
+  /* TODO: We might want something more consistent with custom color and standard colors. */
+  if (frame < frameCurrent) {
+    if (use_custom_color) {
+      /* Custom color: previous frames color is darker than current frame */
+      interp.color.rgb = customColor * 0.25;
+    }
+    else {
+      /* black - before frameCurrent */
+      if (selected) {
+        intensity = SET_INTENSITY(frameStart, frame, frameCurrent, 0.25, 0.75);
+      }
+      else {
+        intensity = SET_INTENSITY(frameStart, frame, frameCurrent, 0.68, 0.92);
+      }
+      interp.color.rgb = mix(colorWire.rgb, blend_base, intensity);
+    }
+  }
+  else if (frame > frameCurrent) {
+    if (use_custom_color) {
+      /* Custom color: next frames color is equal to user selected color */
+      interp.color.rgb = customColor;
+    }
+    else {
+      /* blue - after frameCurrent */
+      if (selected) {
+        intensity = SET_INTENSITY(frameCurrent, frame, frameEnd, 0.25, 0.75);
+      }
+      else {
+        intensity = SET_INTENSITY(frameCurrent, frame, frameEnd, 0.68, 0.92);
+      }
+
+      interp.color.rgb = mix(colorBonePose.rgb, blend_base, intensity);
+    }
+  }
+  else {
+    if (use_custom_color) {
+      /* Custom color: current frame color is slightly darker than user selected color */
+      interp.color.rgb = customColor * 0.5;
+    }
+    else {
+      /* green - on frameCurrent */
+      if (selected) {
+        intensity = 0.92f;
+      }
+      else {
+        intensity = 0.75f;
+      }
+      interp.color.rgb = mix(colorBackground.rgb, blend_base, intensity);
+    }
+  }
+
+  interp.color.a = 1.0;
+
+  view_clipping_distances(pos);
+}