Clear color attachment if FCE was invoked before any draws (#1851)

* Clear RT if FCE was invoked before any draws

Co-authored-by: psucien <bad_cast@protonmail.com>

* address review comments

---------

Co-authored-by: psucien <bad_cast@protonmail.com>

src/video_core/renderer_vulkan/vk_rasterizer.cpp

@@ -52,7 +52,8 @@ bool Rasterizer::FilterDraw() {
     // There are several cases (e.g. FCE, FMask/HTile decompression) where we don't need to do an
     // actual draw hence can skip pipeline creation.
     if (regs.color_control.mode == Liverpool::ColorControl::OperationMode::EliminateFastClear) {
-        LOG_TRACE(Render_Vulkan, "FCE pass skipped");
+        // Clears the render target if FCE is launched before any draws
+        EliminateFastClear();
         return false;
     }
     if (regs.color_control.mode == Liverpool::ColorControl::OperationMode::FmaskDecompress) {
@@ -201,6 +202,34 @@ RenderState Rasterizer::PrepareRenderState(u32 mrt_mask) {
     return {vertex_offset, instance_offset};
 }
 
+void Rasterizer::EliminateFastClear() {
+    auto& col_buf = liverpool->regs.color_buffers[0];
+    if (!col_buf || !col_buf.info.fast_clear) {
+        return;
+    }
+    if (!texture_cache.IsMetaCleared(col_buf.CmaskAddress(), col_buf.view.slice_start)) {
+        return;
+    }
+    for (u32 slice = col_buf.view.slice_start; slice <= col_buf.view.slice_max; ++slice) {
+        texture_cache.TouchMeta(col_buf.CmaskAddress(), slice, false);
+    }
+    const auto& hint = liverpool->last_cb_extent[0];
+    VideoCore::TextureCache::RenderTargetDesc desc(col_buf, hint);
+    const auto& image_view = texture_cache.FindRenderTarget(desc);
+    const auto& image = texture_cache.GetImage(image_view.image_id);
+    const vk::ImageSubresourceRange range = {
+        .aspectMask = vk::ImageAspectFlagBits::eColor,
+        .baseMipLevel = 0,
+        .levelCount = 1,
+        .baseArrayLayer = col_buf.view.slice_start,
+        .layerCount = col_buf.view.slice_max - col_buf.view.slice_start + 1,
+    };
+    scheduler.EndRendering();
+    scheduler.CommandBuffer().clearColorImage(image.image, vk::ImageLayout::eColorAttachmentOptimal,
+                                              LiverpoolToVK::ColorBufferClearValue(col_buf).color,
+                                              range);
+}
+
 void Rasterizer::Draw(bool is_indexed, u32 index_offset) {
     RENDERER_TRACE;
 

src/video_core/renderer_vulkan/vk_rasterizer.h

@@ -71,6 +71,7 @@ private:
     RenderState PrepareRenderState(u32 mrt_mask);
     void BeginRendering(const GraphicsPipeline& pipeline, RenderState& state);
     void Resolve();
+    void EliminateFastClear();
 
     void UpdateDynamicState(const GraphicsPipeline& pipeline);
     void UpdateViewportScissorState();