Lay the light cluster tiles over the window when the post processing is skippe; Bind the light cluster buffers when a viewport is created

docs/clustered-lighting.md

@@ -86,7 +86,9 @@ reverse-Z with the far plane at infinity, so the `znear` / `zfar` of the pass bo
 `cluster_cull.comp` handles one cluster per invocation and goes through `lights[1 .. lights_total)`.
 
 - A light's reach is the distance where its brightest possible contribution falls under `MIN_CONTRIBUTION`
-  (1/1024) of the display range, at most `MAX_RANGE` (1000 m, as the 1 km filter on the CPU). Headlights are tested against
+  (1/1024) of the display range. There is no fixed limit on top of that: the 1 km filter on the CPU is the distance
+  of a light from the camera, and the shading lights a surface at any distance, so a headlight without falloff
+  reaches every cluster in its beam. Headlights are tested against
   that sphere and against the frustum of their projection (four side planes and the near plane, with 5 cm of margin);
   point lights against a sphere; spot lights against a sphere and a cone; directional lights reach everything.
 - A cluster takes up to 64 lights. The ones that come first in `lights[]` win, which is the order from

rendering/opengl46/opengl46renderer.cpp

@@ -464,6 +464,10 @@ bool opengl46_renderer::init_viewport(viewport_config &vp)
 	light_ssbo->bind_base();
 
 	vp.clusters = std::make_unique<gl::cluster_grid>();
+	// the material shaders declare the cluster blocks whether they read them or not, and drawing with an active storage
+	// block without a buffer behind it is undefined. the context starts with these buffers in place; every pass which
+	// uses a grid binds its own
+	vp.clusters->bind();
 
 	if (!Global.gfx_skippipeline)
 	{
@@ -941,7 +945,8 @@ void opengl46_renderer::Render_pass(viewport_config &vp, rendermode const Mode)
         // the environment map is drawn in
         auto const clusterlists{ Global.gfx_lights_clustered || Global.gfx_lights_clusterheatmap };
         if( clusterlists ) {
-            Update_Clusters( vp );
+            // the tiles are laid over what the scene is drawn to: the buffers of the viewport, or the window itself without the post processing pipeline
+            Update_Clusters( vp, Global.gfx_skippipeline ? target_size : glm::ivec2{ vp.width, vp.height } );
         }
         Update_Lights( simulation::Lights, true, Global.gfx_lights_clustered && vp.clusters->valid() );
         if( clusterlists ) {
@@ -6086,14 +6091,14 @@ void opengl46_renderer::Update_Lights(light_array &Lights, bool const Headlights
 	light_ssbo->update(&light_data, 0, offsetof(gl::light_data, lights) + sizeof(gl::light_element) * light_i);
 }
 
-void opengl46_renderer::Update_Clusters(viewport_config &vp)
+void opengl46_renderer::Update_Clusters(viewport_config &vp, glm::ivec2 const &Targetsize)
 {
 	glDebug("Update_Clusters");
 
 	auto &grid{*vp.clusters};
 	grid.bind();
 	// the boxes of the clusters depend only on the projection and the depth range, so they are rebuilt only when those change
-	if (grid.update(OpenGLMatrices.data(GL_PROJECTION), m_renderpass.znear, m_renderpass.zfar, glm::vec2{static_cast<float>(vp.width), static_cast<float>(vp.height)}))
+	if (grid.update(OpenGLMatrices.data(GL_PROJECTION), m_renderpass.znear, m_renderpass.zfar, glm::vec2{Targetsize}))
 	{
 		m_clusterstimer.begin();
 		grid.build(*m_cluster_build_shader);

rendering/opengl46/opengl46renderer.h

@@ -345,8 +345,9 @@ class opengl46_renderer : public gfx_renderer {
 	// unless Headlights is false, as in the pass which draws the environment map, where lights of vehicles would only get baked into the map.
 	// Clustered tells the shading to take the headlights from the lists of the clusters (see Cull_Lights()) and not to go through the first few
 	void Update_Lights(light_array &Lights, bool const Headlights = true, bool const Clustered = false);
-	// brings the light cluster grid of the viewport up to date with the projection of the color pass being drawn
-	void Update_Clusters(viewport_config &vp);
+	// brings the light cluster grid of the viewport up to date with the projection of the color pass being drawn.
+	// Targetsize is the size in pixels of what the pass draws to, which gl_FragCoord of the shading counts in
+	void Update_Clusters(viewport_config &vp, glm::ivec2 const &Targetsize);
 	// assigns the lights set up by Update_Lights() to the clusters of the viewport; run after it, before the scene is drawn
 	void Cull_Lights(viewport_config &vp);
 	// debug view: tints the finished image of the viewport with the cluster of every pixel. Target is the framebuffer