feat: add lookAt function

src/cam.c

@@ -34,3 +34,29 @@ Vec4f_t* viewport_r(Vec4f_t* vec, float width, float height)
     vec->y = (1.f - vec->y) * 0.5f * height;
     return vec;
 }
+
+Mat4f_t lookAt(Vec4f_t* eye, Vec4f_t* center, Vec4f_t* up)
+{
+    Vec4f_t f = vec4f_sub(*center, *eye);
+    f.data[3] = 0.f;
+    f = vec4f_scale(f, 1.f / vec4f_len(f));
+
+    Vec4f_t s = vec4f_cross(f, *up);
+    s.data[3] = 0.f;
+    s = vec4f_scale(s, 1.f / vec4f_len(s));
+
+    Vec4f_t u = vec4f_cross(s, f);
+    u.data[3] = 0.f;
+
+    const float m[16] = {
+        s.x,  u.x,  -f.x,  0.f,
+        s.y,  u.y,  -f.y,  0.f,
+        s.z,  u.z,  -f.z,  0.f,
+       -vec4f_dot(s, *eye),
+       -vec4f_dot(u, *eye),
+        vec4f_dot(f, *eye),
+        1.f
+    };
+
+    return mat4f_from_array(m);
+}

src/math/mat4.h

@@ -4,24 +4,29 @@
 #define MAT_SIZE 16
 #define MAT_DIM 4
 
+#ifndef SIMD 
 #if defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) 
     #define SIMD_X86
+
 #elif defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64)
     #define SIMD_ARCH
+
 #else
 #endif
+#define SIMD
+#endif
 
 #ifdef _MSC_VER
-    #define ALIGN16 __declspec(align(MAT_SIZE))
+    #define ALIGN16_MAT __declspec(align(MAT_SIZE))
 #else
-    #define ALIGN16 __attribute__((aligned(MAT_SIZE)))
+    #define ALIGN16_MAT __attribute__((aligned(MAT_SIZE)))
 #endif
 
 
 typedef struct 
 {
     float m[MAT_SIZE];
-} ALIGN16 Mat4f_t;
+} ALIGN16_MAT Mat4f_t;
 
 Mat4f_t* mat4f_from_array_r(Mat4f_t *__restrict m, const float arr[MAT_SIZE]);
 

src/math/vec3.h

@@ -9,29 +9,33 @@
 #define vec3_h
 
 
+#ifndef SIMD 
 #if defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) 
     #define SIMD_X86
-    #include <xmmintrin.h>
 
 #elif defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64)
     #define SIMD_ARCH
-    #include <arm_neon.h>
 
 #else
 #endif
+#define SIMD
+#endif
 
+#ifndef ALIGN16_VEC
 #ifdef _MSC_VER
-    #define ALIGN16 __declspec(align(16))
+    #define ALIGN16_VEC __declspec(align(16))
 #else
-    #define ALIGN16 __attribute__((aligned(16)))
+    #define ALIGN16_VEC __attribute__((aligned(16)))
 #endif
+#endif
+
 
 #define VEC_SIZE 3
 
 typedef union {
     struct { float x, y, z; };
     float data[4];
-} ALIGN16 Vec3f_t;
+} ALIGN16_VEC Vec3f_t;
 
 Vec3f_t vec3f_from_array(const float *__restrict val);
 Vec3f_t vec3f(float x, float y, float z);

src/math/vec4.c

@@ -209,8 +209,8 @@ Vec4f_t vec4f_lerp(Vec4f_t a, Vec4f_t b, float t)
     return a;
 }
 
- float vec4f_angle(Vec4f_t a, Vec4f_t b)
- {
+float vec4f_angle(Vec4f_t a, Vec4f_t b)
+{
     float lenA = vec4f_len(a);
     float lenB = vec4f_len(b);
 
@@ -225,29 +225,45 @@ Vec4f_t vec4f_lerp(Vec4f_t a, Vec4f_t b, float t)
     cosTheta = fmaxf(-1.f, fminf(cosTheta, 1.f));
 
     return acosf(cosTheta);
- }
+}
 
 
- Vec4f_t vec4f_proj(Vec4f_t a, Vec4f_t b)
- {
+Vec4f_t vec4f_proj(Vec4f_t a, Vec4f_t b)
+{
     float dotA = vec4f_dot(a, b);
     float dotB = vec4f_dot(b, b);
 
     float scale = dotA / dotB;
     return vec4f_scale(b, scale);
- }
+}
 
- Vec4f_t vec4f_refl(Vec4f_t v, Vec4f_t normal)
- {
+Vec4f_t vec4f_refl(Vec4f_t v, Vec4f_t normal)
+{
     Vec4f_t proj = vec4f_proj(v, normal);
     Vec4f_t scal = vec4f_scale(proj, 2.f);
     Vec4f_t rlt = vec4f_sub(v, scal);
     return rlt;
- }
+}
 
- float vec4f_dist(Vec4f_t a, Vec4f_t b)
- {
+float vec4f_dist(Vec4f_t a, Vec4f_t b)
+{
     Vec4f_t vsub = vec4f_sub(a, b);
     float rlt = vec4f_len(vsub);
     return rlt;
- }
+}
+
+Vec4f_t* vec4f_cross_r(Vec4f_t* __restrict out, Vec4f_t a, Vec4f_t b)
+{
+    out->x = a.y * b.z - a.z * b.y;
+    out->y = a.z * b.x - a.x * b.z;
+    out->z = a.x * b.y - a.y * b.x;
+    out->w = 0.f;
+    return out;
+}
+
+Vec4f_t vec4f_cross(Vec4f_t a, Vec4f_t b)
+{
+    Vec4f_t out;
+    vec4f_cross_r(&out, a, b);
+    return out;
+}

src/math/vec4.h

@@ -1,6 +1,7 @@
 #ifndef VECTOR4_H
 #define VECTOR4_H
 
+#ifndef SIMD 
 #if defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) 
     #define SIMD_X86
 
@@ -9,11 +10,16 @@
 
 #else
 #endif
+#define SIMD
+#endif
 
+
+#ifndef ALIGN16_VEC
 #ifdef _MSC_VER
-    #define ALIGN16 __declspec(align(16))
+    #define ALIGN16_VEC __declspec(align(16))
 #else
-    #define ALIGN16 __attribute__((aligned(16)))
+    #define ALIGN16_VEC __attribute__((aligned(16)))
+#endif
 #endif
 
 #define VEC_SIZE 4
@@ -25,7 +31,7 @@ typedef union
 {
     struct { float x, y, z, w; };
     float data[VEC_SIZE];
-} ALIGN16 Vec4f_t;
+} ALIGN16_VEC Vec4f_t;
 
 Vec4f_t vec4f_from_array(const float *__restrict val);
 Vec4f_t vec4f(float x, float y, float z, float w);
@@ -66,6 +72,10 @@ Vec4f_t vec4f_refl(Vec4f_t v, Vec4f_t normal);
 
 float vec4f_dist(Vec4f_t a, Vec4f_t b);
 
+Vec4f_t* vec4f_cross_r(Vec4f_t* __restrict out, Vec4f_t a, Vec4f_t b);
+
+Vec4f_t vec4f_cross(Vec4f_t a, Vec4f_t b);
+
 #undef VEC_SIZE
 
 #endif // VECTOR4_H