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Add rotation

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This commit is contained in:
Miloslav Číž 2018-11-20 15:27:47 +01:00
parent e330136046
commit aff771d1cc
1 changed files with 46 additions and 5 deletions
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51
s3l.h
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@ -10,6 +10,10 @@
--------------------
CONVENTIONS:
Angles are in S3L_Units, a full angle (2 pi) is S3L_FRACTIONS_PER_UNITs.
COORDINATE SYSTEMS:
In 3D space, a left-handed coord. system is used. One spatial unit is split
@ -91,7 +95,10 @@ static inline void S3L_initVec3(S3L_Vec3 *v)
typedef struct
{
S3L_Vec3 offset;
S3L_Vec3 rotation;
S3L_Vec3 rotation; /**< Euler angles. Rortation is applied in this order:
1. z = around z (roll) CW looking along z+
2. x = around x (pitch) CW looking along x+
3. y = around y (yaw) CW looking along y+ */
S3L_Vec3 scale;
} S3L_Transform3D;
@ -223,17 +230,24 @@ static inline S3L_Unit S3L_nonZero(S3L_Unit value)
static inline S3L_Unit S3L_sin(S3L_Unit x)
{
x = S3L_wrap(x / S3L_SIN_TABLE_UNIT_STEP,S3L_SIN_TABLE_LENGTH * 4);
int8_t positive = 1;
if (x < S3L_SIN_TABLE_LENGTH)
x = x;
else if (x < S3L_SIN_TABLE_LENGTH * 2)
x = S3L_SIN_TABLE_LENGTH * 2 - x - 1;
else if (x < S3L_SIN_TABLE_LENGTH * 3)
{
x = x - S3L_SIN_TABLE_LENGTH * 2;
positive = 0;
}
else
{
x = S3L_SIN_TABLE_LENGTH - (x - S3L_SIN_TABLE_LENGTH * 3) - 1;
positive = 0;
}
return S3L_sinTable[x];
return positive ? S3L_sinTable[x] : -1 * S3L_sinTable[x];
}
static inline S3L_Unit S3L_cos(S3L_Unit x)
@ -595,12 +609,39 @@ void S3L_drawTriangle(
#undef stepSide
}
static inline void S3L_rotate2DPoint(S3L_Unit *x, S3L_Unit *y, S3L_Unit angle)
{
if (angle < S3L_SIN_TABLE_UNIT_STEP)
return; // no visible rotation
S3L_Unit angleSin = S3L_sin(angle);
S3L_Unit angleCos = S3L_cos(angle);
S3L_Unit xBackup = *x;
*x =
(angleCos * (*x)) / S3L_FRACTIONS_PER_UNIT -
(angleSin * (*y)) / S3L_FRACTIONS_PER_UNIT;
*y =
(angleSin * xBackup) / S3L_FRACTIONS_PER_UNIT +
(angleCos * (*y)) / S3L_FRACTIONS_PER_UNIT;
}
static inline void S3L_mapModelToWorld(S3L_Vec3 point,
S3L_Transform3D *modelTransform, S3L_Vec3 *newPoint)
{
newPoint->x = point.x + modelTransform->offset.x;
newPoint->y = point.y + modelTransform->offset.y;
newPoint->z = point.z + modelTransform->offset.z;
newPoint->x = point.x;
newPoint->y = point.y;
newPoint->z = point.z;
S3L_rotate2DPoint(&(newPoint->x),&(newPoint->y),modelTransform->rotation.z);
S3L_rotate2DPoint(&(newPoint->z),&(newPoint->y),modelTransform->rotation.x);
S3L_rotate2DPoint(&(newPoint->z),&(newPoint->x),modelTransform->rotation.y);
newPoint->x += modelTransform->offset.x;
newPoint->y += modelTransform->offset.y;
newPoint->z += modelTransform->offset.z;
}
static inline void S3L_mapWorldToCamera(S3L_Vec3 point,