1 files changed, 60 insertions, 0 deletions
diff --git a/gfx/gl/shaders/directionalLight.frag b/gfx/gl/shaders/directionalLight.frag
new file mode 100644
index 0000000..e5ebfb0
--- /dev/null
+++ b/gfx/gl/shaders/directionalLight.frag
@@ -0,0 +1,60 @@
+#version 460 core
+
+const int MAX_MAPS = 4;
+
+out vec3 FragColor;
+
+in vec2 TexCoords;
+
+layout(binding = 0) uniform isampler2D gPosition;
+layout(binding = 1) uniform sampler2D gNormal;
+layout(binding = 2) uniform sampler2DArray shadowMap;
+
+uniform vec3 lightDirection;
+uniform vec3 lightColour;
+uniform ivec3 lightPoint;
+uniform mat4 lightViewProjection[MAX_MAPS];
+uniform uint lightViewProjectionCount;
+
+float
+getShadow(vec3 positionInLightSpace, float m, vec2 texelSize)
+{
+	float shadow = 0.0;
+	for (float x = -texelSize.x; x <= texelSize.x; x += texelSize.x) {
+		for (float y = -texelSize.y; y <= texelSize.y; y += texelSize.y) {
+			const float lightSpaceDepth = texture(shadowMap, vec3(positionInLightSpace.xy + vec2(x, y), m)).r;
+			shadow += step(positionInLightSpace.z, lightSpaceDepth + 0.001);
+		}
+	}
+	return shadow / 9.0;
+}
+
+float
+insideShadowCube(vec3 v, vec2 texelSize)
+{
+	const vec3 s = step(vec3(texelSize, 0), v) - step(vec3(1 - texelSize, 1), v);
+	return s.x * s.y * s.z;
+}
+
+float
+isShaded(vec4 Position)
+{
+	const vec2 texelSize = 1.0 / textureSize(shadowMap, 0).xy;
+	for (uint m = 0u; m < lightViewProjectionCount; m++) {
+		const vec3 positionInLightSpace = (lightViewProjection[m] * Position).xyz;
+		const float inside = insideShadowCube(positionInLightSpace, texelSize);
+		if (inside > 0) {
+			return getShadow(positionInLightSpace, m, texelSize);
+		}
+	}
+	return 1.0;
+}
+
+void
+main()
+{
+	const vec4 Position = vec4(texture(gPosition, TexCoords).xyz - lightPoint, 1);
+	const vec3 Normal = texture(gNormal, TexCoords).rgb;
+	const float shaded = isShaded(Position);
+	FragColor = shaded * max(dot(-lightDirection, Normal) * lightColour, 0);
+}