diff options
| -rw-r--r-- | chickadee/math/matrix.scm | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/chickadee/math/matrix.scm b/chickadee/math/matrix.scm index 6931a2c..f16e583 100644 --- a/chickadee/math/matrix.scm +++ b/chickadee/math/matrix.scm @@ -51,6 +51,8 @@ matrix4-identity! orthographic-projection perspective-projection + look-at! + look-at matrix4-translate! matrix4-translate matrix4-scale! @@ -540,6 +542,27 @@ clipping plane NEAR and FAR." 0 0 (/ (+ far near) (- near far)) -1 0 0 (/ (* 2 far near) (- near far)) 0))) +(define (look-at! matrix eye at up) + ;; TODO: Eliminate allocation of vectors. + (let* ((zaxis (vec3-normalize (vec3- at eye))) + (xaxis (vec3-normalize (vec3-cross zaxis (vec3-normalize up)))) + (yaxis (vec3-cross xaxis zaxis))) + (init-matrix4 matrix + (vec3-x xaxis) (vec3-x yaxis) (- (vec3-x zaxis)) 0.0 + (vec3-y xaxis) (vec3-y yaxis) (- (vec3-y zaxis)) 0.0 + (vec3-z xaxis) (vec3-z yaxis) (- (vec3-z zaxis)) 0.0 + (- (vec3-dot-product xaxis eye)) + (- (vec3-dot-product yaxis eye)) + (vec3-dot-product zaxis eye) + 1.0))) + +(define (look-at eye at up) + "Return a new matrix4 that looks toward the position AT from the +position EYE, with the top of the viewport facing UP." + (let ((matrix (make-null-matrix4))) + (look-at! matrix eye at up) + matrix)) + (define (matrix4-translate! matrix v) (cond ((vec2? v) |