Add lerp

dqnt.h

@@ -49,6 +49,11 @@ typedef float  f32;
 #define DQNT_SQUARED(x) ((x) * (x))
 #define DQNT_SQRT(x) (sqrtf(x))
 
+////////////////////////////////////////////////////////////////////////////////
+// Math
+////////////////////////////////////////////////////////////////////////////////
+DQNT_FILE_SCOPE f32 dqnt_lerp(f32 a, f32 t, f32 b);
+
 ////////////////////////////////////////////////////////////////////////////////
 // Vec2
 ////////////////////////////////////////////////////////////////////////////////
@@ -214,7 +219,26 @@ DQNT_FILE_SCOPE i32  dqnt_rnd_pcg_range(DqntRandPCGState *pcg, i32 min, i32 max)
 	#define WIN32_LEAN_AND_MEAN
 #endif
 
+////////////////////////////////////////////////////////////////////////////////
+// Math
+////////////////////////////////////////////////////////////////////////////////
+DQNT_FILE_SCOPE f32 dqnt_lerp(f32 a, f32 t, f32 b)
+{
+	/*
+	    Linear blend between two values. We having a starting point "a", and
+	    the distance to "b" is defined as (b - a). Then we can say
 
+	    a + t(b - a)
+
+	    As our linear blend fn. We start from "a" and choosing a t from 0->1
+	    will vary the value of (b - a) towards b. If we expand this, this
+	    becomes
+
+	    a + (t * b) - (a * t) == (1 - t)a + t*b
+	*/
+	f32 result =  a + (b - a) * t;
+	return result;
+}
 
 ////////////////////////////////////////////////////////////////////////////////
 // Vec2

dqnt_unit_test.cpp

@@ -293,6 +293,29 @@ void dqnt_random_test() {
 	printf("dqnt_random_test(): Completed successfully\n");
 }
 
+void dqnt_math_test()
+{
+	{ // Lerp
+		{
+			f32 start = 10;
+			f32 t     = 0.5f;
+			f32 end   = 20;
+			DQNT_ASSERT(dqnt_lerp(start, t, end) == 15);
+		}
+
+		{
+			f32 start = 10;
+			f32 t     = 2.0f;
+			f32 end   = 20;
+			DQNT_ASSERT(dqnt_lerp(start, t, end) == 30);
+		}
+
+		printf("dqnt_math_test(): lerp: Completed successfully\n");
+	}
+
+	printf("dqnt_math_test(): Completed successfully\n");
+}
+
 void dqnt_vec_test()
 {
 	{ // V2
@@ -438,7 +461,12 @@ int main(void)
 {
 	dqnt_strings_test();
 	dqnt_random_test();
+	dqnt_math_test();
 	dqnt_vec_test();
 	dqnt_other_test();
+
+	printf("\nPress Any Key to Exit\n");
+	getchar();
+
 	return 0;
 }