Add texture tri-linear autodiff example. (#2715)

* Add quad texture example.

* delete output image

* remove irrelavent files

* update project files

* fix

* Update example.

* Fix.

* remove out-texture

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/examples/autodiff-texture/reconstruct.slang b/examples/autodiff-texture/reconstruct.slang
new file mode 100644
index 000000000..c123010e5
--- /dev/null
+++ b/examples/autodiff-texture/reconstruct.slang
@@ -0,0 +1,48 @@
+// A compute shader to propagate gradients from high level mip(low-res) to lower level mip (high-res).
+
+cbuffer Uniforms
+{
+    uint4 mipOffset[16];
+    uint dstLayer;
+    uint layerCount;
+    uint width;
+    uint height;
+    RWStructuredBuffer<int> accumulateBuffer;
+    RWStructuredBuffer<float> dstBuffer;
+}
+
+[shader("compute")]
+[numthreads(16, 16, 1)]
+void computeMain(uint3 threadIdx : SV_DispatchThreadID)
+{
+    uint x = threadIdx.x;
+    uint y = threadIdx.y;
+    uint dstW = width >> dstLayer;
+    uint dstH = height >> dstLayer;
+    if (x >= dstW) return;
+    if (y >= dstH) return;
+    uint dstOffset = mipOffset[dstLayer / 4][dstLayer % 4] + (y * dstW + x) * 4;
+    var dstVal = int4(accumulateBuffer[dstOffset], accumulateBuffer[dstOffset + 1], accumulateBuffer[dstOffset + 2], accumulateBuffer[dstOffset + 3]);
+    var newDstValToAdd = float3(0.0);
+    if (dstVal.w > 0)
+        newDstValToAdd = (float3)dstVal.xyz * float3(1.0 / (dstVal.w * 65536.0));
+
+    float4 existingVal = 0.0;
+    
+    if (dstLayer < layerCount - 1 )
+    {
+        uint parentOffset = mipOffset[(dstLayer + 1) / 4][(dstLayer + 1) % 4];
+        uint parentW = dstW / 2;
+        uint parentPixelLoc = parentOffset + ((y / 2) * parentW + (x / 2)) * 4;
+        existingVal.x = dstBuffer[parentPixelLoc] * 0.25;
+        existingVal.y = dstBuffer[parentPixelLoc + 1] * 0.25;
+        existingVal.z = dstBuffer[parentPixelLoc + 2] * 0.25;
+        existingVal.w = 0.0;
+    }
+
+    var newDstVal = existingVal + float4(newDstValToAdd, 0.0);
+    dstBuffer[dstOffset] = newDstVal.x;
+    dstBuffer[dstOffset + 1] = newDstVal.y;
+    dstBuffer[dstOffset + 2] = newDstVal.z;
+    dstBuffer[dstOffset + 3] = 1.0;
+}