EEVEE: Refactor curve nodes

This patches rewrites the GPU shaders of curve nodes for easier future
development. This is a non-functional change. The new code avoids code
duplication by moving common code into BKE curve mapping functions. It
also avoids ambiguous data embedding into the gradient vectors that are
passed to vectors and reduces the size of uniforms uploaded to the
shader by avoiding redundancies.

This is needed in preparation for the viewport compositor, which will
utilize and extend this implementation.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D14689

1 files changed, 74 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/colortools.c b/source/blender/blenkernel/intern/colortools.c
index c3d66d4463d..e4c46703f8a 100644
--- a/source/blender/blenkernel/intern/colortools.c
+++ b/source/blender/blenkernel/intern/colortools.c
@@ -1158,6 +1158,80 @@ bool BKE_curvemapping_RGBA_does_something(const CurveMapping *cumap)
   return false;
 }
 
+void BKE_curvemapping_get_range_minimums(const CurveMapping *curve_mapping, float minimums[CM_TOT])
+{
+  for (int i = 0; i < CM_TOT; i++) {
+    minimums[i] = curve_mapping->cm[i].mintable;
+  }
+}
+
+void BKE_curvemapping_compute_range_dividers(const CurveMapping *curve_mapping,
+                                             float dividers[CM_TOT])
+{
+  for (int i = 0; i < CM_TOT; i++) {
+    const CurveMap *curve_map = &curve_mapping->cm[i];
+    dividers[i] = 1.0f / max_ff(1e-8f, curve_map->maxtable - curve_map->mintable);
+  }
+}
+
+void BKE_curvemapping_compute_slopes(const CurveMapping *curve_mapping,
+                                     float start_slopes[CM_TOT],
+                                     float end_slopes[CM_TOT])
+{
+  float range_dividers[CM_TOT];
+  BKE_curvemapping_compute_range_dividers(curve_mapping, range_dividers);
+  for (int i = 0; i < CM_TOT; i++) {
+    const CurveMap *curve_map = &curve_mapping->cm[i];
+    /* If extrapolation is not enabled, the slopes are horizontal. */
+    if (!(curve_mapping->flag & CUMA_EXTEND_EXTRAPOLATE)) {
+      start_slopes[i] = 0.0f;
+      end_slopes[i] = 0.0f;
+      continue;
+    }
+
+    if (curve_map->ext_in[0] != 0.0f) {
+      start_slopes[i] = curve_map->ext_in[1] / (curve_map->ext_in[0] * range_dividers[i]);
+    }
+    else {
+      start_slopes[i] = 1e8f;
+    }
+
+    if (curve_map->ext_out[0] != 0.0f) {
+      end_slopes[i] = curve_map->ext_out[1] / (curve_map->ext_out[0] * range_dividers[i]);
+    }
+    else {
+      end_slopes[i] = 1e8f;
+    }
+  }
+}
+
+bool BKE_curvemapping_is_map_identity(const CurveMapping *curve_mapping, int index)
+{
+  if (!(curve_mapping->flag & CUMA_EXTEND_EXTRAPOLATE)) {
+    return false;
+  }
+  const CurveMap *curve_map = &curve_mapping->cm[index];
+  if (curve_map->maxtable - curve_map->mintable != 1.0f) {
+    return false;
+  }
+  if (curve_map->ext_in[0] != curve_map->ext_in[1]) {
+    return false;
+  }
+  if (curve_map->ext_out[0] != curve_map->ext_out[1]) {
+    return false;
+  }
+  if (curve_map->totpoint != 2) {
+    return false;
+  }
+  if (curve_map->curve[0].x != 0 || curve_map->curve[0].y != 0) {
+    return false;
+  }
+  if (curve_map->curve[1].x != 0 || curve_map->curve[1].y != 0) {
+    return false;
+  }
+  return true;
+}
+
 void BKE_curvemapping_init(CurveMapping *cumap)
 {
   int a;