Stabilize Vulkan shadow pipeline diagnostics and compatibility path

- Fix shadow depth image layout transitions by tracking per-frame old/new layouts.
- Update receiver shadow projection to Vulkan clip-depth convention.
- Test inverted shadow compare op path (GREATER_OR_EQUAL).
- Switch shadow compare samplers to NEAREST filtering for broader Vulkan compatibility.
- Expand shadow caster coverage by disabling caster cull filtering in WMO/M2/Character shadow pipelines.
- Keep light-space matrix path on stable character-centered framing.

assets/shaders/character.frag.glsl

@@ -63,9 +63,12 @@ void main() {
         float shadow = 1.0;
         if (shadowParams.x > 0.5) {
             vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
-            vec3 proj = lsPos.xyz / lsPos.w * 0.5 + 0.5;
+            vec3 proj = lsPos.xyz / lsPos.w;
-            if (proj.z <= 1.0) {
+            proj.xy = proj.xy * 0.5 + 0.5;
-                float bias = max(0.005 * (1.0 - dot(norm, ldir)), 0.001);
+            if (proj.x >= 0.0 && proj.x <= 1.0 &&
+                proj.y >= 0.0 && proj.y <= 1.0 &&
+                proj.z >= 0.0 && proj.z <= 1.0) {
+                float bias = max(0.0005 * (1.0 - dot(norm, ldir)), 0.00005);
                 shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
             }
             shadow = mix(1.0, shadow, shadowParams.y);

assets/shaders/m2.frag.glsl

@@ -86,9 +86,12 @@ void main() {
         float shadow = 1.0;
         if (shadowParams.x > 0.5) {
             vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
-            vec3 proj = lsPos.xyz / lsPos.w * 0.5 + 0.5;
+            vec3 proj = lsPos.xyz / lsPos.w;
-            if (proj.z <= 1.0) {
+            proj.xy = proj.xy * 0.5 + 0.5;
-                float bias = max(0.005 * (1.0 - abs(dot(norm, ldir))), 0.001);
+            if (proj.x >= 0.0 && proj.x <= 1.0 &&
+                proj.y >= 0.0 && proj.y <= 1.0 &&
+                proj.z >= 0.0 && proj.z <= 1.0) {
+                float bias = max(0.0005 * (1.0 - abs(dot(norm, ldir))), 0.00005);
                 shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
             }
             shadow = mix(1.0, shadow, shadowParams.y);

assets/shaders/terrain.frag.glsl

@@ -84,7 +84,7 @@ void main() {
         vec3 proj = lsPos.xyz / lsPos.w;
         proj.xy = proj.xy * 0.5 + 0.5;
         if (proj.x >= 0.0 && proj.x <= 1.0 && proj.y >= 0.0 && proj.y <= 1.0 && proj.z <= 1.0) {
-            float bias = 0.002;
+            float bias = 0.0002;
             shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
             shadow = mix(1.0, shadow, shadowParams.y);
         }

assets/shaders/wmo.frag.glsl

@@ -57,9 +57,12 @@ void main() {
         float shadow = 1.0;
         if (shadowParams.x > 0.5) {
             vec4 lsPos = lightSpaceMatrix * vec4(FragPos, 1.0);
-            vec3 proj = lsPos.xyz / lsPos.w * 0.5 + 0.5;
+            vec3 proj = lsPos.xyz / lsPos.w;
-            if (proj.z <= 1.0) {
+            proj.xy = proj.xy * 0.5 + 0.5;
-                float bias = max(0.005 * (1.0 - dot(norm, ldir)), 0.001);
+            if (proj.x >= 0.0 && proj.x <= 1.0 &&
+                proj.y >= 0.0 && proj.y <= 1.0 &&
+                proj.z >= 0.0 && proj.z <= 1.0) {
+                float bias = max(0.0005 * (1.0 - dot(norm, ldir)), 0.00005);
                 shadow = texture(uShadowMap, vec3(proj.xy, proj.z - bias));
             }
             shadow = mix(1.0, shadow, shadowParams.y);

include/rendering/renderer.hpp

@@ -233,6 +233,7 @@ private:
     VkSampler shadowSampler = VK_NULL_HANDLE;
     VkRenderPass shadowRenderPass = VK_NULL_HANDLE;
     VkFramebuffer shadowFramebuffer = VK_NULL_HANDLE;
+    VkImageLayout shadowDepthLayout_ = VK_IMAGE_LAYOUT_UNDEFINED;
     glm::mat4 lightSpaceMatrix = glm::mat4(1.0f);
     glm::vec3 shadowCenter = glm::vec3(0.0f);
     bool shadowCenterInitialized = false;

src/rendering/character_renderer.cpp

@@ -2087,9 +2087,9 @@ bool CharacterRenderer::initializeShadow(VkRenderPass shadowRenderPass) {
                     fragShader.stageInfo(VK_SHADER_STAGE_FRAGMENT_BIT))
         .setVertexInput({vertBind}, vertAttrs)
         .setTopology(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST)
-        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_FRONT_BIT)
+        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_NONE)
         .setDepthTest(true, true, VK_COMPARE_OP_LESS_OR_EQUAL)
-        .setDepthBias(2.0f, 4.0f)
+        .setDepthBias(0.05f, 0.20f)
         .setNoColorAttachment()
         .setLayout(shadowPipelineLayout_)
         .setRenderPass(shadowRenderPass)

src/rendering/m2_renderer.cpp

@@ -2603,9 +2603,11 @@ bool M2Renderer::initializeShadow(VkRenderPass shadowRenderPass) {
                     fragShader.stageInfo(VK_SHADER_STAGE_FRAGMENT_BIT))
         .setVertexInput({vertBind}, vertAttrs)
         .setTopology(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST)
-        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_FRONT_BIT)
+        // Foliage/leaf cards are effectively two-sided; front-face culling can
+        // drop them from the shadow map depending on light/view orientation.
+        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_NONE)
         .setDepthTest(true, true, VK_COMPARE_OP_LESS_OR_EQUAL)
-        .setDepthBias(2.0f, 4.0f)
+        .setDepthBias(0.05f, 0.20f)
         .setNoColorAttachment()
         .setLayout(shadowPipelineLayout_)
         .setRenderPass(shadowRenderPass)
@@ -2655,9 +2657,10 @@ void M2Renderer::renderShadow(VkCommandBuffer cmd, const glm::mat4& lightSpaceMa
         vkCmdPushConstants(cmd, shadowPipelineLayout_, VK_SHADER_STAGE_VERTEX_BIT,
                            0, 128, &push);
 
-        // Draw only opaque batches
+        // Draw all batches in shadow pass.
+        // Blend-mode filtering was excluding many valid world casters after
+        // Vulkan material path changes (trees/buildings losing shadows).
         for (const auto& batch : model.batches) {
-            if (batch.blendMode >= 2) continue;  // skip transparent
             if (batch.submeshLevel > 0) continue; // skip LOD submeshes
             vkCmdDrawIndexed(cmd, batch.indexCount, 1, batch.indexStart, 0, 0);
         }

src/rendering/renderer.cpp

@@ -288,6 +288,7 @@ bool Renderer::createPerFrameResources() {
         LOG_ERROR("Failed to create shadow depth image");
         return false;
     }
+    shadowDepthLayout_ = VK_IMAGE_LAYOUT_UNDEFINED;
 
     // --- Create shadow depth image view ---
     VkImageViewCreateInfo viewCI{};
@@ -304,15 +305,15 @@ bool Renderer::createPerFrameResources() {
     // --- Create shadow sampler ---
     VkSamplerCreateInfo sampCI{};
     sampCI.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
-    sampCI.magFilter = VK_FILTER_LINEAR;
+    sampCI.magFilter = VK_FILTER_NEAREST;
-    sampCI.minFilter = VK_FILTER_LINEAR;
+    sampCI.minFilter = VK_FILTER_NEAREST;
     sampCI.mipmapMode = VK_SAMPLER_MIPMAP_MODE_NEAREST;
     sampCI.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     sampCI.addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     sampCI.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     sampCI.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
     sampCI.compareEnable = VK_TRUE;
-    sampCI.compareOp = VK_COMPARE_OP_LESS_OR_EQUAL;
+    sampCI.compareOp = VK_COMPARE_OP_GREATER_OR_EQUAL;
     if (vkCreateSampler(device, &sampCI, nullptr, &shadowSampler) != VK_SUCCESS) {
         LOG_ERROR("Failed to create shadow sampler");
         return false;
@@ -326,7 +327,7 @@ bool Renderer::createPerFrameResources() {
     depthAtt.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
     depthAtt.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
     depthAtt.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
-    depthAtt.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+    depthAtt.initialLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
     depthAtt.finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
 
     VkAttachmentReference depthRef{};
@@ -501,6 +502,7 @@ void Renderer::destroyPerFrameResources() {
     if (shadowDepthView) { vkDestroyImageView(device, shadowDepthView, nullptr); shadowDepthView = VK_NULL_HANDLE; }
     if (shadowDepthImage) { vmaDestroyImage(vkCtx->getAllocator(), shadowDepthImage, shadowDepthAlloc); shadowDepthImage = VK_NULL_HANDLE; shadowDepthAlloc = VK_NULL_HANDLE; }
     if (shadowSampler) { vkDestroySampler(device, shadowSampler, nullptr); shadowSampler = VK_NULL_HANDLE; }
+    shadowDepthLayout_ = VK_IMAGE_LAYOUT_UNDEFINED;
 }
 
 void Renderer::updatePerFrameUBO() {
@@ -3699,19 +3701,25 @@ void Renderer::renderShadowPass() {
         ubo->shadowParams = glm::vec4(shadowsEnabled ? 1.0f : 0.0f, 0.8f, 0.0f, 0.0f);
     }
 
-    // Barrier 1: UNDEFINED → DEPTH_STENCIL_ATTACHMENT_OPTIMAL
+    // Barrier 1: transition shadow map into writable depth layout.
     VkImageMemoryBarrier b1{};
     b1.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
-    b1.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+    b1.oldLayout = shadowDepthLayout_;
     b1.newLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
     b1.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
     b1.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-    b1.srcAccessMask = 0;
+    b1.srcAccessMask = (shadowDepthLayout_ == VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL)
-    b1.dstAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
+        ? VK_ACCESS_SHADER_READ_BIT
+        : 0;
+    b1.dstAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT |
+                       VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;
     b1.image = shadowDepthImage;
     b1.subresourceRange = {VK_IMAGE_ASPECT_DEPTH_BIT, 0, 1, 0, 1};
+    VkPipelineStageFlags srcStage = (shadowDepthLayout_ == VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL)
+        ? VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT
+        : VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
     vkCmdPipelineBarrier(currentCmd,
-        VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT,
+        srcStage, VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT,
         0, 0, nullptr, 0, nullptr, 1, &b1);
 
     // Begin shadow render pass
@@ -3758,6 +3766,7 @@ void Renderer::renderShadowPass() {
     vkCmdPipelineBarrier(currentCmd,
         VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT,
         0, 0, nullptr, 0, nullptr, 1, &b2);
+    shadowDepthLayout_ = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
 }
 
 } // namespace rendering

src/rendering/vk_texture.cpp

@@ -249,14 +249,14 @@ bool VkTexture::createSampler(VkDevice device,
 bool VkTexture::createShadowSampler(VkDevice device) {
     VkSamplerCreateInfo samplerInfo{};
     samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
-    samplerInfo.minFilter = VK_FILTER_LINEAR;
+    samplerInfo.minFilter = VK_FILTER_NEAREST;
-    samplerInfo.magFilter = VK_FILTER_LINEAR;
+    samplerInfo.magFilter = VK_FILTER_NEAREST;
     samplerInfo.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     samplerInfo.addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     samplerInfo.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
     samplerInfo.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
     samplerInfo.compareEnable = VK_TRUE;
-    samplerInfo.compareOp = VK_COMPARE_OP_LESS_OR_EQUAL;
+    samplerInfo.compareOp = VK_COMPARE_OP_GREATER_OR_EQUAL;
     samplerInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_NEAREST;
     samplerInfo.minLod = 0.0f;
     samplerInfo.maxLod = 1.0f;

src/rendering/wmo_renderer.cpp

@@ -1486,9 +1486,9 @@ bool WMORenderer::initializeShadow(VkRenderPass shadowRenderPass) {
                     fragShader.stageInfo(VK_SHADER_STAGE_FRAGMENT_BIT))
         .setVertexInput({vertBind}, vertAttrs)
         .setTopology(VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST)
-        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_FRONT_BIT)
+        .setRasterization(VK_POLYGON_MODE_FILL, VK_CULL_MODE_NONE)
         .setDepthTest(true, true, VK_COMPARE_OP_LESS_OR_EQUAL)
-        .setDepthBias(2.0f, 4.0f)
+        .setDepthBias(0.05f, 0.20f)
         .setNoColorAttachment()
         .setLayout(shadowPipelineLayout_)
         .setRenderPass(shadowRenderPass)
@@ -1535,9 +1535,10 @@ void WMORenderer::renderShadow(VkCommandBuffer cmd, const glm::mat4& lightSpaceM
             vkCmdBindVertexBuffers(cmd, 0, 1, &group.vertexBuffer, &offset);
             vkCmdBindIndexBuffer(cmd, group.indexBuffer, 0, VK_INDEX_TYPE_UINT16);
 
-            // Draw only opaque batches (skip transparent)
+            // Draw all batches in shadow pass.
+            // WMO transparency classification is not reliable enough for caster
+            // selection here and was dropping major world casters.
             for (const auto& mb : group.mergedBatches) {
-                if (mb.isTransparent) continue;
                 for (const auto& dr : mb.draws) {
                     vkCmdDrawIndexed(cmd, dr.indexCount, 1, dr.firstIndex, 0, 0);
                 }