Cycles: Initial support of 3D textures for CUDA rendering

Supports both smoke/fire and point density textures now.

Reduces number of textures available for sm_20 and sm_21, but you have
to compromise somewhere on such a limited hardware.

Currently limited to linear interpolation only, and decoupled ray
marching is not supported yet. Think those could be considered just a
further improvement.

Some quick example:

  https://developer.blender.org/F282934

Code is minimal and we can fully consider it a fix for missing
support of 3D textures with CUDA.

Reviewers: lukasstockner97, brecht, juicyfruit, dingto

Reviewed By: brecht, juicyfruit, dingto

Subscribers: mib2berlin

Differential Revision: https://developer.blender.org/D1806

intern/cycles/kernel/kernel_compat_cuda.h

@@ -62,6 +62,7 @@ typedef texture<int, 1> texture_int;
 typedef texture<uint4, 1> texture_uint4;
 typedef texture<uchar4, 1> texture_uchar4;
 typedef texture<float4, 2> texture_image_float4;
+typedef texture<float4, 3> texture_image3d_float4;
 typedef texture<uchar4, 2, cudaReadModeNormalizedFloat> texture_image_uchar4;
 
 /* Macros to handle different memory storage on different devices */
@@ -79,6 +80,7 @@ typedef texture<uchar4, 2, cudaReadModeNormalizedFloat> texture_image_uchar4;
 #define kernel_tex_fetch(t, index) t[(index)]
 #endif
 #define kernel_tex_image_interp(t, x, y) tex2D(t, x, y)
+#define kernel_tex_image_interp_3d(t, x, y, z) tex3D(t, x, y, z)
 
 #define kernel_data __data