Discard writes to outside of texture bounds

According to GLSL spec calling imageStore with coordinates outside of
texture bounds has no effect, but on Intel GPUs it actually results in
writes inside the texture, causing an incorrect result. Now the writes
are bounds-checked.

CHANGELOG.md

@@ -6,6 +6,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Writes to the outside of the result texture end up back inside the texture
+  on some Intel GPUs on Linux. Now they are correctly discarded again.
+
 ## 4.0.0 - 2021-08-25
 
 ### Added

src/haloray-core/resources/shaders/raytrace.glsl

@@ -771,6 +771,9 @@ void main(void)
     vec2 projected = camera.focalLength * projectionFunction * vec2(aspectRatio * cos(polarAngle), sin(polarAngle));
     vec2 normalizedCoordinates = 0.5 + projected;
 
+    if (any(lessThanEqual(normalizedCoordinates, vec2(0.0))) || any(greaterThanEqual(normalizedCoordinates, vec2(1.0))))
+        return;
+
     float sunRadiance;
     if (atmosphereEnabled == 1)
     {