bilbo/d3d10
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

collada_scene: cubic bezier interpolation

Browse Source
This commit is contained in:
Zack Buhman 2026-01-27 18:10:01 -06:00
parent b0906ecdc6
commit 6a2a74a0f6
2 changed files with 80 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
src/collada_scene.cpp
View File

@ -374,6 +374,73 @@ namespace collada_scene {
return prev + iv * (next - prev);
}
static inline float pow3(float f)
{
return f * f * f;
}
static inline float pow2(float f)
{
return f * f;
}
static inline XMVECTOR bezier(XMVECTOR p0, XMVECTOR c0, XMVECTOR c1, XMVECTOR p1, float s)
{
return
p0 * pow3(1 - s)
+ 3 * c0 * s * pow2(1 - s)
+ 3 * c1 * pow2(s) * (1 - s)
+ p1 * pow3(s);
}
static inline float bezier_binary_search(XMVECTOR p0, XMVECTOR c0, XMVECTOR c1, XMVECTOR p1, float want)
{
float low = 0.0f;
float high = 1.0f;
int iterations = 0;
while (iterations < 20) {
iterations += 1;
float s = (high + low) * 0.5f;
XMVECTOR bs = bezier(p0, c0, c1, p1, s);
float t = XMVectorGetX(bs);
const float epsilon = 0.001f;
if (fabsf(t - want) < epsilon) {
return XMVectorGetY(bs);
}
if (t > want) {
high = s;
} else {
low = s;
}
}
print("%f %f\n", XMVectorGetX(p0), XMVectorGetY(p0));
print("%f %f\n", XMVectorGetX(c0), XMVectorGetY(c0));
print("%f %f\n", XMVectorGetX(c1), XMVectorGetY(c1));
print("%f %f\n", XMVectorGetX(p1), XMVectorGetY(p1));
assert(false);
}
static float bezier_sampler(sampler const * const sampler, int ix, float t)
{
/*
P0 is (INPUT[i] , OUTPUT[i])
C0 (or T0) is (OUT_TANGENT[i][0] , OUT_TANGENT[i][1])
C1 (or T1) is (IN_TANGENT[i+1][0], IN_TANGENT[i+1][1])
P1 is (INPUT[i+1], OUTPUT[i+1])
*/
XMVECTOR p0 = XMVectorSet(sampler->input.float_array[ix], sampler->output.float_array[ix], 0, 0);
XMVECTOR c0 = XMLoadFloat2((XMFLOAT2 *)&sampler->out_tangent.float2_array[ix]);
XMVECTOR c1 = XMLoadFloat2((XMFLOAT2 *)&sampler->in_tangent.float2_array[ix+1]);
XMVECTOR p1 = XMVectorSet(sampler->input.float_array[ix+1], sampler->output.float_array[ix+1], 0, 0);
return bezier_binary_search(p0, c0, c1, p1, t);
}
static void animate_node(node const& node, node_instance& node_instance, float t)
{
for (int i = 0; i < node.channels_count; i++) {
@ -384,8 +451,17 @@ namespace collada_scene {
if (frame_ix < 0)
continue; // animation is missing a key frame
float iv = interpolation_value(channel.source_sampler->input, frame_ix, t);
float value = linear_interpolate(channel.source_sampler->output, frame_ix, iv);
enum collada::interpolation const * const interpolation =
channel.source_sampler->interpolation.interpolation_array;
float value;
if (interpolation[frame_ix] == interpolation::BEZIER) {
value = bezier_sampler(channel.source_sampler, frame_ix, t);
} else {
float iv = interpolation_value(channel.source_sampler->input, frame_ix, t);
value = linear_interpolate(channel.source_sampler->output, frame_ix, iv);
}
switch (transform.type) {
case transform_type::TRANSLATE:
switch (channel.target_attribute) {

4
src/main.cpp
View File

@ -129,8 +129,8 @@ XMFLOAT4 g_vLightColors[2] = {
//
XMVECTOR g_Eye = XMVectorSet(0.0f, -30.0f, 15.0f, 1.0f);
XMVECTOR g_At = XMVectorSet(0.0f, 0.0f, 15.0f, 1.0f);
XMVECTOR g_Eye = XMVectorSet(0.0f, -3.0f, 13.0f, 1.0f);
XMVECTOR g_At = XMVectorSet(0.0f, 0.0f, 0.0f, 1.0f);
// collada scene state