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#include <assert.h>
#include "sig.h"
typedef struct ops_lerp_ctxt_t {
sig_sig_t *a, *b, *t;
} ops_lerp_ctxt_t;
static size_t ops_lerp_size(va_list ap)
{
return sizeof(ops_lerp_ctxt_t);
}
/* Supply two sig_sig_t's to be interpolated and another for the t, this sig_sig_t
* takes ownership of them so they'll be freed on destroy when the ops_lerp
* sig_sig_t is freed.
*/
static void ops_lerp_init(void *context, va_list ap)
{
ops_lerp_ctxt_t *ctxt = context;
assert(ctxt);
ctxt->a = va_arg(ap, sig_sig_t *);
ctxt->b = va_arg(ap, sig_sig_t *);
ctxt->t = va_arg(ap, sig_sig_t *);
}
static void ops_lerp_destroy(void *context)
{
ops_lerp_ctxt_t *ctxt = context;
assert(ctxt);
sig_free(ctxt->a);
sig_free(ctxt->b);
sig_free(ctxt->t);
}
static inline float lerp(float a, float b, float t)
{
return (1.f - t) * a + b * t;
}
static float ops_lerp_output(void *context, unsigned ticks_ms)
{
ops_lerp_ctxt_t *ctxt = context;
assert(ctxt);
return lerp(sig_output(ctxt->a, ticks_ms),
sig_output(ctxt->b, ticks_ms),
sig_output(ctxt->t, ticks_ms));
}
sig_ops_t sig_ops_lerp = {
.size = ops_lerp_size,
.init = ops_lerp_init,
.destroy = ops_lerp_destroy,
.output = ops_lerp_output,
};
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