GPU: Split gpu_shader_material into multiple files.

This patch continue the efforts to split the `gpu_shader_material` file
started in D5569.

Dependency resolution is now recursive. Each shading node gets its own
file. Additionally, some utility files are added to be shared between
files, like `math_util`, `color_util`, and `hash`. Some files are always
included because they may be used in the execution function, like
`world_normals`.

Some glsl functions appeared to be unused, so they were removed, like
`output_node`, `bits_to_01`, and `exp_blender`. Other functions have
been renamed to be more general and get used as utils, like `texco_norm`
which became `vector_normalize`.

A lot of the opengl tests fails, but those same tests also fail in
master, so this is probably unrelated to this patch.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D5616

1 files changed, 37 insertions, 0 deletions

diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_fresnel.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_fresnel.glsl
new file mode 100644
index 00000000000..7a4d28f2dd6
--- /dev/null
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_fresnel.glsl
@@ -0,0 +1,37 @@
+float fresnel_dielectric_cos(float cosi, float eta)
+{
+  /* compute fresnel reflectance without explicitly computing
+   * the refracted direction */
+  float c = abs(cosi);
+  float g = eta * eta - 1.0 + c * c;
+  float result;
+
+  if (g > 0.0) {
+    g = sqrt(g);
+    float A = (g - c) / (g + c);
+    float B = (c * (g + c) - 1.0) / (c * (g - c) + 1.0);
+    result = 0.5 * A * A * (1.0 + B * B);
+  }
+  else {
+    result = 1.0; /* TIR (no refracted component) */
+  }
+
+  return result;
+}
+
+float fresnel_dielectric(vec3 Incoming, vec3 Normal, float eta)
+{
+  /* compute fresnel reflectance without explicitly computing
+   * the refracted direction */
+  return fresnel_dielectric_cos(dot(Incoming, Normal), eta);
+}
+
+void node_fresnel(float ior, vec3 N, vec3 I, out float result)
+{
+  N = normalize(N);
+  /* handle perspective/orthographic */
+  vec3 I_view = (ProjectionMatrix[3][3] == 0.0) ? normalize(I) : vec3(0.0, 0.0, -1.0);
+
+  float eta = max(ior, 0.00001);
+  result = fresnel_dielectric(I_view, N, (gl_FrontFacing) ? eta : 1.0 / eta);
+}