Palette interpolation on device

cuburn/code/interp.py

@@ -313,6 +313,33 @@ void test_cr(const float *times, const float *knots, const float *t, float *r) {
     r[i] = catmull_rom(times, knots, t[i]);
 }
 
+__global__
+void interp_palette_hsv(uchar4 *outs, const float *times, const float4 *sources,
+        float tstart, float tstep) {
+    float time = tstart + blockIdx.x * tstep;
+    int idx = fmaxf(bitwise_binsearch(times, time), 1);
 
+    float4 left  = sources[blockDim.x * (idx - 1) + threadIdx.x];
+    float4 right = sources[blockDim.x * (idx)     + threadIdx.x];
+
+    float lf = (times[idx] - time) / (times[idx] - times[idx-1]);
+    float rf = 1.0f - lf;
+
+    float3 lhsv = rgb2hsv(make_float3(left.x, left.y, left.z));
+    float3 rhsv = rgb2hsv(make_float3(right.x, right.y, right.z));
+
+    float3 hsv;
+    hsv.x = lhsv.x * lf + rhsv.x * rf;
+    hsv.y = lhsv.y * lf + rhsv.y * rf;
+    hsv.z = lhsv.z * lf + rhsv.z * rf;
+    float3 rgb = hsv2rgb(hsv);
+
+    uchar4 out;
+    out.x = rgb.x * 255.0f;
+    out.y = rgb.y * 255.0f;
+    out.z = rgb.z * 255.0f;
+    out.w = 255.0f * (left.z * lf + right.z * rf);
+    outs[blockDim.x * blockIdx.x + threadIdx.x] = out;
+}
 """)
 

cuburn/code/util.py

@@ -35,6 +35,11 @@ class BaseCode(HunkOCode):
 #include<cuda.h>
 #include<stdint.h>
 #include<stdio.h>
+"""
+
+    decls = """
+float3 rgb2hsv(float3 rgb);
+float3 hsv2rgb(float3 hsv);
 """
 
     defs = r"""
@@ -134,7 +139,49 @@ void write_half(float &xy, float x, float y, float den) {
         : "=f"(xy) : "f"(x), "f"(y), "f"(den));
 }
 
+__device__
+float3 rgb2hsv(float3 rgb) {
+    float M = fmaxf(fmaxf(rgb.x, rgb.y), rgb.z);
+    float m = fminf(fminf(rgb.x, rgb.y), rgb.z);
+    float C = M - m;
 
+    float s = M > 0.0f ? C / M : 0.0f;
+
+    float h;
+    if (s != 0.0f) {
+        C = 1.0f / C;
+        float rc = (M - rgb.x) * C;
+        float gc = (M - rgb.y) * C;
+        float bc = (M - rgb.z) * C;
+
+        if      (rgb.x == M)  h = bc - gc;
+        else if (rgb.y == M)  h = 2 + gc - bc;
+        else                  h = 4 + gc - rc;
+
+        if (h < 0) h += 6;
+    }
+    return make_float3(h, s, M);
+}
+
+__device__
+float3 hsv2rgb(float3 hsv) {
+
+    float whole = floorf(hsv.x);
+    float frac = hsv.x - whole;
+    float val = hsv.z;
+    float min = val * (1 - hsv.y);
+    float mid = val * (1 - (hsv.y * frac));
+    float alt = val * (1 - (hsv.y * (1 - frac)));
+
+    float3 out;
+         if (whole == 0.0f) { out.x = val; out.y = alt; out.z = min; }
+    else if (whole == 1.0f) { out.x = mid; out.y = val; out.z = min; }
+    else if (whole == 2.0f) { out.x = min; out.y = val; out.z = alt; }
+    else if (whole == 3.0f) { out.x = min; out.y = mid; out.z = val; }
+    else if (whole == 4.0f) { out.x = alt; out.y = min; out.z = val; }
+    else                    { out.x = val; out.y = min; out.z = mid; }
+    return out;
+}
 """
 
     @staticmethod