We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Implement reusable GLSL functions for color space transformations
At least RGB <-> HSV. Put them in `vispy.visuals.glsl`.


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `vispy/visuals/glsl/color.py`
Content:
```
1 """Color-related GLSL functions."""
2 
3 
4 # -----------------------------------------------------------------------------
5 # Colormaps
6 # -----------------------------------------------------------------------------
7 
8 """Texture lookup for a discrete color map stored in a 1*ncolors 2D texture.
9 
10 The `get_color()` function returns a RGB color from an index integer
11 referring to the colormap.
12 
13 
14 Inputs
15 ------
16 
17 index (int): The color index.
18 
19 
20 Template variables
21 ------------------
22 
23 $ncolors (int): The number of colors in the colormap.
24 
25 $colormap (2D texture sampler): The sampler for the 2D 1*ncolors colormap
26     texture.
27 
28 
29 Outputs
30 -------
31 
32 color (vec3): The color.
33 
34 """
35 COLORMAP_TEXTURE = """
36 vec3 get_color(int index) {
37     float x = (float(index) + .5) / float($ncolors);
38     return texture2D($colormap, vec2(x, .5)).rgb;
39 }
40 """
41
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/vispy/visuals/glsl/color.py b/vispy/visuals/glsl/color.py
--- a/vispy/visuals/glsl/color.py
+++ b/vispy/visuals/glsl/color.py
@@ -38,3 +38,33 @@
     return texture2D($colormap, vec2(x, .5)).rgb;
 }
 """
+
+
+# -----------------------------------------------------------------------------
+# Color space transformations
+# -----------------------------------------------------------------------------
+
+# From http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl
+# TODO: unit tests
+HSV_TO_RGB = """
+vec3 hsv_to_rgb(vec3 c)
+{
+    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
+    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
+    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
+}
+"""
+
+
+RGB_TO_HSV = """
+vec3 rgb_to_hsv(vec3 c)
+{
+    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
+    vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
+    vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
+
+    float d = q.x - min(q.w, q.y);
+    float e = 1.0e-10;
+    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
+}
+"""

{"golden_diff": "diff --git a/vispy/visuals/glsl/color.py b/vispy/visuals/glsl/color.py\n--- a/vispy/visuals/glsl/color.py\n+++ b/vispy/visuals/glsl/color.py\n@@ -38,3 +38,33 @@\n     return texture2D($colormap, vec2(x, .5)).rgb;\n }\n \"\"\"\n+\n+\n+# -----------------------------------------------------------------------------\n+# Color space transformations\n+# -----------------------------------------------------------------------------\n+\n+# From http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl\n+# TODO: unit tests\n+HSV_TO_RGB = \"\"\"\n+vec3 hsv_to_rgb(vec3 c)\n+{\n+    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);\n+    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);\n+    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);\n+}\n+\"\"\"\n+\n+\n+RGB_TO_HSV = \"\"\"\n+vec3 rgb_to_hsv(vec3 c)\n+{\n+    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);\n+    vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));\n+    vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));\n+\n+    float d = q.x - min(q.w, q.y);\n+    float e = 1.0e-10;\n+    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);\n+}\n+\"\"\"\n", "issue": "Implement reusable GLSL functions for color space transformations\nAt least RGB <-> HSV. Put them in `vispy.visuals.glsl`.\n\n", "before_files": [{"content": "\"\"\"Color-related GLSL functions.\"\"\"\n\n\n# -----------------------------------------------------------------------------\n# Colormaps\n# -----------------------------------------------------------------------------\n\n\"\"\"Texture lookup for a discrete color map stored in a 1*ncolors 2D texture.\n\nThe `get_color()` function returns a RGB color from an index integer\nreferring to the colormap.\n\n\nInputs\n------\n\nindex (int): The color index.\n\n\nTemplate variables\n------------------\n\n$ncolors (int): The number of colors in the colormap.\n\n$colormap (2D texture sampler): The sampler for the 2D 1*ncolors colormap\n    texture.\n\n\nOutputs\n-------\n\ncolor (vec3): The color.\n\n\"\"\"\nCOLORMAP_TEXTURE = \"\"\"\nvec3 get_color(int index) {\n    float x = (float(index) + .5) / float($ncolors);\n    return texture2D($colormap, vec2(x, .5)).rgb;\n}\n\"\"\"\n", "path": "vispy/visuals/glsl/color.py"}], "after_files": [{"content": "\"\"\"Color-related GLSL functions.\"\"\"\n\n\n# -----------------------------------------------------------------------------\n# Colormaps\n# -----------------------------------------------------------------------------\n\n\"\"\"Texture lookup for a discrete color map stored in a 1*ncolors 2D texture.\n\nThe `get_color()` function returns a RGB color from an index integer\nreferring to the colormap.\n\n\nInputs\n------\n\nindex (int): The color index.\n\n\nTemplate variables\n------------------\n\n$ncolors (int): The number of colors in the colormap.\n\n$colormap (2D texture sampler): The sampler for the 2D 1*ncolors colormap\n    texture.\n\n\nOutputs\n-------\n\ncolor (vec3): The color.\n\n\"\"\"\nCOLORMAP_TEXTURE = \"\"\"\nvec3 get_color(int index) {\n    float x = (float(index) + .5) / float($ncolors);\n    return texture2D($colormap, vec2(x, .5)).rgb;\n}\n\"\"\"\n\n\n# -----------------------------------------------------------------------------\n# Color space transformations\n# -----------------------------------------------------------------------------\n\n# From http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl\n# TODO: unit tests\nHSV_TO_RGB = \"\"\"\nvec3 hsv_to_rgb(vec3 c)\n{\n    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);\n    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);\n    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);\n}\n\"\"\"\n\n\nRGB_TO_HSV = \"\"\"\nvec3 rgb_to_hsv(vec3 c)\n{\n    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);\n    vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));\n    vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));\n\n    float d = q.x - min(q.w, q.y);\n    float e = 1.0e-10;\n    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);\n}\n\"\"\"\n", "path": "vispy/visuals/glsl/color.py"}]}