Merge pull request #364 from jmiskovic/fix/lookat

Add mat4:targetAt and modify the mat4:lookAt

src/api/l_math_vectors.c

@@ -1655,6 +1655,16 @@ static int l_lovrMat4LookAt(lua_State* L) {
   return 1;
 }
 
+static int l_lovrMat4Target(lua_State* L) {
+  mat4 m = luax_checkvector(L, 1, V_MAT4, NULL);
+  vec3 from = luax_checkvector(L, 2, V_VEC3, NULL);
+  vec3 to = luax_checkvector(L, 3, V_VEC3, NULL);
+  vec3 up = lua_isnoneornil(L, 4) ? (float[4]) { 0.f, 1.f, 0.f } : luax_checkvector(L, 4, V_VEC3, NULL);
+  mat4_target(m, from, to, up);
+  lua_settop(L, 1);
+  return 1;
+}
+
 static int l_lovrMat4__mul(lua_State* L) {
   mat4 m = luax_checkvector(L, 1, V_MAT4, NULL);
   VectorType type;
@@ -1738,6 +1748,7 @@ const luaL_Reg lovrMat4[] = {
   { "perspective", l_lovrMat4Perspective },
   { "fov", l_lovrMat4Fov },
   { "lookAt", l_lovrMat4LookAt },
+  { "target", l_lovrMat4Target },
   { "__mul", l_lovrMat4__mul },
   { "__tostring", l_lovrMat4__tostring },
   { "__newindex", l_lovrMat4__newindex },

src/core/maf.h

@@ -625,6 +625,32 @@ MAF void mat4_getFov(mat4 m, float* left, float* right, float* up, float* down)
 }
 
 MAF mat4 mat4_lookAt(mat4 m, vec3 from, vec3 to, vec3 up) {
+  float x[4];
+  float y[4];
+  float z[4];
+  vec3_normalize(vec3_sub(vec3_init(z, from), to));
+  vec3_normalize(vec3_cross(vec3_init(x, up), z));
+  vec3_cross(vec3_init(y, z), x);
+  m[0] = x[0];
+  m[1] = y[0];
+  m[2] = z[0];
+  m[3] = 0.f;
+  m[4] = x[1];
+  m[5] = y[1];
+  m[6] = z[1];
+  m[7] = 0.f;
+  m[8] = x[2];
+  m[9] = y[2];
+  m[10] = z[2];
+  m[11] = 0.f;
+  m[12] = -vec3_dot(x, from);
+  m[13] = -vec3_dot(y, from);
+  m[14] = -vec3_dot(z, from);
+  m[15] = 1.f;
+  return m;
+}
+
+MAF mat4 mat4_target(mat4 m, vec3 from, vec3 to, vec3 up) {
   float x[4];
   float y[4];
   float z[4];
@@ -643,9 +669,9 @@ MAF mat4 mat4_lookAt(mat4 m, vec3 from, vec3 to, vec3 up) {
   m[9] = z[1];
   m[10] = z[2];
   m[11] = 0.f;
-  m[12] = -vec3_dot(x, from);
-  m[13] = -vec3_dot(y, from);
-  m[14] = -vec3_dot(z, from);
+  m[12] = from[0];
+  m[13] = from[1];
+  m[14] = from[2];
   m[15] = 1.f;
   return m;
 }