EDIT: Forward-Z cascaded shadow map

shaders/deferred_lighting.frag

@@ -80,8 +80,11 @@ float calcShadowVisibility(vec3 worldPos, vec3 N, vec3 L)
 
         float mapD = texture(shadowTex[ci], suv + off).r;
 
-        // Standard depth shadow map: occluded when current > mapD + bias
+        // Forward-Z depth shadow map:
-        float occ  = step(current + bias, mapD);
+        //  - Occluded when current + bias > mapD
+        //  - Unoccluded otherwise
+        // Use step(edge, x): returns 1 when x >= edge. Make occ=1 for occluded.
+        float occ  = step(mapD + bias, current);
 
         occluded += occ * w;
         wsum     += w;
@@ -161,7 +164,7 @@ void main(){
     vec3 kD = (1.0 - kS) * (1.0 - metallic);
 
     float NdotL = max(dot(N, L), 0.0);
-    // Shadowing (directional, reversed-Z shadow map)
+    // Shadowing (directional, forward-Z shadow map)
     float visibility = calcShadowVisibility(pos, N, L);
 
     vec3 irradiance = sceneData.sunlightColor.rgb * sceneData.sunlightColor.a * NdotL * visibility;

src/render/vk_renderpass_shadow.cpp

@@ -45,11 +45,11 @@ void ShadowPass::init(EngineContext *context)
         b.set_cull_mode(VK_CULL_MODE_BACK_BIT, VK_FRONT_FACE_CLOCKWISE);
         b.set_multisampling_none();
         b.disable_blending();
-        // Reverse-Z depth test for shadow maps (clear=0.0, GREATER_OR_EQUAL)
+        // Forward-Z for shadow maps only (engine uses reversed-Z elsewhere)
-        b.enable_depthtest(true, VK_COMPARE_OP_GREATER_OR_EQUAL);
+        // We clear depth to 1.0 and use LESS_OR_EQUAL so the nearest depth wins.
+        b.enable_depthtest(true, VK_COMPARE_OP_LESS_OR_EQUAL);
         b.set_depth_format(VK_FORMAT_D32_SFLOAT);
 
-        // Static depth bias to help with surface acne (tune later)
         b._rasterizer.depthBiasEnable = VK_TRUE;
         b._rasterizer.depthBiasConstantFactor = 2.0f;
         b._rasterizer.depthBiasSlopeFactor = 2.0f;
@@ -85,8 +85,8 @@ void ShadowPass::register_graph(RenderGraph *graph, std::span<RGImageHandle> cas
             RGPassType::Graphics,
             [shadowDepth](RGPassBuilder &builder, EngineContext *ctx)
             {
-                // Reverse-Z depth clear to 0.0
+                // Forward-Z in shadow pass: clear depth to 1.0 (far)
-                VkClearValue clear{}; clear.depthStencil = {0.f, 0};
+                VkClearValue clear{}; clear.depthStencil = {1.f, 0};
                 builder.write_depth(shadowDepth, true, clear);
 
                 // Ensure index/vertex buffers are tracked as reads (like Geometry)

src/scene/vk_scene.cpp

@@ -110,7 +110,9 @@ void SceneManager::update_scene()
     {
         using namespace glm;
         const vec3 camPos = vec3(inverse(view)[3]);
-        vec3 L = normalize(-vec3(sceneData.sunlightDirection));
+        // Use light-ray direction (from light to scene).
+        // Shaders compute per-fragment L as -sunlightDirection (vector to light).
+        vec3 L = normalize(vec3(sceneData.sunlightDirection));
         if (!glm::all(glm::isfinite(L)) || glm::length2(L) < 1e-10f)
             L = glm::vec3(0.0f, -1.0f, 0.0f);