Cycles: Add Support for IES files as textures for light strength

This patch adds support for IES files, a file format that is commonly used to store the directional intensity distribution of light sources.
The new IES node is supposed to be plugged into the Strength input of the Emission node of the lamp.

Since people generating IES files do not really seem to care about the standard, the parser is flexible enough to accept all test files I have tried.
Some common weirdnesses are distributing values over multiple lines that should go into one line, using commas instead of spaces as delimiters and adding various useless stuff at the end of the file.

The user interface of the node is similar to the script node, the user can either select an internal Text or load a file.
Internally, IES files are handled similar to Image textures: They are stored in slots by the LightManager and each unique IES is assigned to one slot.

The local coordinate system of the lamp is used, so that the direction of the light can be changed. For UI reasons, it's usually best to add an area light,
rotate it and then change its type, since especially the point light does not immediately show its local coordinate system in the viewport.

Reviewers: #cycles, dingto, sergey, brecht

Reviewed By: #cycles, dingto, brecht

Subscribers: OgDEV, crazyrobinhood, secundar, cardboard, pisuke, intrah, swerner, micah_denn, harvester, gottfried, disnel, campbellbarton, duarteframos, Lapineige, brecht, juicyfruit, dingto, marek, rickyblender, bliblubli, lockal, sergey

Differential Revision: https://developer.blender.org/D1543

1 files changed, 9 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 8d3ab29a2fb..95101ac1e51 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -893,6 +893,12 @@ typedef struct NodeShaderUVMap {
 	char uv_map[64];
 } NodeShaderUVMap;
 
+typedef struct NodeShaderTexIES {
+	int mode;
+
+	char filepath[1024]; /* 1024 = FILE_MAX */
+} NodeShaderTexIES;
+
 typedef struct NodeSunBeams {
 	float source[2];
 
@@ -906,6 +912,9 @@ typedef struct NodeSunBeams {
 /* script node flag */
 #define NODE_SCRIPT_AUTO_UPDATE		1
 
+/* ies node mode */
+#define NODE_IES_INTERNAL		0
+#define NODE_IES_EXTERNAL		1
 
 /* frame node flags */
 #define NODE_FRAME_SHRINK		1	/* keep the bounding box minimal */