1 files changed, 78 insertions, 0 deletions
diff --git a/src/include/libplacebo/shaders/lut.h b/src/include/libplacebo/shaders/lut.h
new file mode 100644
index 0000000..6e30ddc
--- /dev/null
+++ b/src/include/libplacebo/shaders/lut.h
@@ -0,0 +1,78 @@
+/*
+ * This file is part of libplacebo.
+ *
+ * libplacebo is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * libplacebo is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with libplacebo.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBPLACEBO_SHADERS_LUT_H_
+#define LIBPLACEBO_SHADERS_LUT_H_
+
+// Shaders for loading and applying arbitrary custom 1D/3DLUTs
+
+#include <libplacebo/colorspace.h>
+#include <libplacebo/shaders.h>
+
+PL_API_BEGIN
+
+// Struct defining custom LUTs
+//
+// Note: Users may freely create their own instances of this struct, there is
+// nothing particularly special about `pl_lut_parse_cube`.
+struct pl_custom_lut {
+    // Some unique signature identifying this LUT, needed to detect state
+    // changes (for cache invalidation). This should ideally be a hash of the
+    // file contents. (Which is what `pl_lut_parse_*` will set it to.)
+    uint64_t signature;
+
+    // Size of each dimension, in the order R, G, B. For 1D LUTs, only the R
+    // dimension should be specified (the others left as 0).
+    int size[3];
+
+    // Raw LUT data itself, in properly scaled floating point format. For 3D
+    // LUTs, the innermost dimension is the first dimension (R), and the
+    // outermost dimension is the last dimension (B). Individual color samples
+    // are in the order R, G, B.
+    const float *data;
+
+    // Extra input/output shaper matrices. Ignored if equal to {0}. This is
+    // mostly useful for 1D LUTs, since 3D LUTs can bake the shaper matrix into
+    // the LUT itself - but it can still help optimize LUT precision.
+    pl_matrix3x3 shaper_in, shaper_out;
+
+    // Nominal metadata for the input/output of a LUT. Left as {0} if unknown.
+    // Note: This is purely informative, `pl_shader_custom_lut` ignores it.
+    struct pl_color_repr repr_in, repr_out;
+    struct pl_color_space color_in, color_out;
+};
+
+// Parse a 3DLUT in .cube format. Returns NULL if the file fails parsing.
+PL_API struct pl_custom_lut *pl_lut_parse_cube(pl_log log, const char *str, size_t str_len);
+
+// Frees a LUT created by `pl_lut_parse_*`.
+PL_API void pl_lut_free(struct pl_custom_lut **lut);
+
+// Apply a `pl_custom_lut`. The user is responsible for ensuring colors going
+// into the LUT are in the expected format as informed by the LUT metadata.
+//
+// `lut_state` must be a pointer to a NULL-initialized shader state object that
+// will be used to encapsulate any required GPU state.
+//
+// Note: `lut` does not have to be allocated by `pl_lut_parse_*`. It can be a
+// struct filled out by the user.
+PL_API void pl_shader_custom_lut(pl_shader sh, const struct pl_custom_lut *lut,
+                                 pl_shader_obj *lut_state);
+
+PL_API_END
+
+#endif // LIBPLACEBO_SHADERS_LUT_H_