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-rw-r--r--3rdparty/bgfx/examples/41-tess/terrain_common.sh99
1 files changed, 99 insertions, 0 deletions
diff --git a/3rdparty/bgfx/examples/41-tess/terrain_common.sh b/3rdparty/bgfx/examples/41-tess/terrain_common.sh
new file mode 100644
index 00000000000..7f6773c1cc2
--- /dev/null
+++ b/3rdparty/bgfx/examples/41-tess/terrain_common.sh
@@ -0,0 +1,99 @@
+#include "bgfx_compute.sh"
+#include "matrices.sh"
+#include "isubd.sh"
+#include "uniforms.sh"
+
+BUFFER_RW(u_AtomicCounterBuffer, uint, 4);
+BUFFER_RW(u_SubdBufferOut, uint, 1);
+
+SAMPLER2D(u_DmapSampler, 0); // displacement map
+SAMPLER2D(u_SmapSampler, 1); // slope map
+
+// displacement map
+float dmap(vec2 pos)
+{
+ return (texture2DLod(u_DmapSampler, pos * 0.5 + 0.5, 0).x) * u_DmapFactor;
+}
+
+float distanceToLod(float z, float lodFactor)
+{
+ // Note that we multiply the result by two because the triangles
+ // edge lengths decreases by half every two subdivision steps.
+ return -2.0 * log2(clamp(z * lodFactor, 0.0f, 1.0f));
+}
+
+float computeLod(vec3 c)
+{
+ //displace
+ c.z += dmap(mtxGetColumn(u_invView, 3).xy);
+
+ vec3 cxf = mul(u_modelView, vec4(c.x, c.y, c.z, 1)).xyz;
+ float z = length(cxf);
+
+ return distanceToLod(z, u_LodFactor);
+}
+
+float computeLod(in vec4 v[3])
+{
+ vec3 c = (v[1].xyz + v[2].xyz) / 2.0;
+ return computeLod(c);
+}
+
+float computeLod(in vec3 v[3])
+{
+ vec3 c = (v[1].xyz + v[2].xyz) / 2.0;
+ return computeLod(c);
+}
+
+void writeKey(uint primID, uint key)
+{
+ uint idx = 0;
+
+ atomicFetchAndAdd(u_AtomicCounterBuffer[0], 2, idx);
+
+ u_SubdBufferOut[idx] = primID;
+ u_SubdBufferOut[idx+1] = key;
+}
+
+void updateSubdBuffer(
+ uint primID
+ , uint key
+ , uint targetLod
+ , uint parentLod
+ , bool isVisible
+ )
+{
+ // extract subdivision level associated to the key
+ uint keyLod = findMSB(key);
+
+ // update the key accordingly
+ if (/* subdivide ? */ keyLod < targetLod && !isLeafKey(key) && isVisible)
+ {
+ uint children[2]; childrenKeys(key, children);
+
+ writeKey(primID, children[0]);
+ writeKey(primID, children[1]);
+ }
+ else if (/* keep ? */ keyLod < (parentLod + 1) && isVisible)
+ {
+ writeKey(primID, key);
+ }
+ else /* merge ? */
+ {
+
+ if (/* is root ? */isRootKey(key))
+ {
+ writeKey(primID, key);
+ }
+
+ else if (/* is zero child ? */isChildZeroKey(key)) {
+ writeKey(primID, parentKey(key));
+ }
+
+ }
+}
+
+void updateSubdBuffer(uint primID, uint key, uint targetLod, uint parentLod)
+{
+ updateSubdBuffer(primID, key, targetLod, parentLod, true);
+}