render: sprite: Add fast path for non-rotated/scaled batched sprites.

* chickadee/render/sprite.scm (sprite-batch-add!): Speed up rendering of
non-rotated, non-scaled sprites by avoid matrix multiplication.

1 files changed, 29 insertions, 20 deletions

diff --git a/chickadee/render/sprite.scm b/chickadee/render/sprite.scm
index 2288edf..318a8a5 100644
--- a/chickadee/render/sprite.scm
+++ b/chickadee/render/sprite.scm
@@ -205,9 +205,9 @@ void main (void) {
 (define sprite-batch-add!
   (let ((tmp-matrix (make-null-matrix4))
         (matrix (make-null-matrix4))
-        (position (vec2 0 0))
-        (world1 (vec2 0 0))
-        (world2 (vec2 0 0))
+        (position (vec2 0.0 0.0))
+        (world1 (vec2 0.0 0.0))
+        (world2 (vec2 0.0 0.0))
         (offset-bv (make-u32vector 1)))
     (define (set-offset offset)
       (u32vector-set! offset-bv 0 offset))
@@ -235,6 +235,8 @@ void main (void) {
                (indices (vertex-buffer-data (sprite-batch-index-buffer batch)))
                (vertices (vertex-buffer-data (sprite-batch-position-buffer batch)))
                (texcoords (vertex-buffer-data (sprite-batch-texture-buffer batch)))
+               (rx (rect-x region))
+               (ry (rect-y region))
                (local-x1 0.0)
                (local-y1 0.0)
                (local-x2 (rect-width region))
@@ -243,23 +245,30 @@ void main (void) {
                (t1 (rect-bottom texture-region))
                (s2 (rect-right texture-region))
                (t2 (rect-top texture-region)))
-          (matrix4-identity! matrix)
-          (when rotation
-            (matrix4-rotate-z! tmp-matrix rotation)
-            (matrix4-mult! matrix matrix tmp-matrix))
-          (when scale
-            (matrix4-scale! tmp-matrix scale)
-            (matrix4-mult! matrix matrix tmp-matrix))
-          (set-vec2-x! position (rect-x region))
-          (set-vec2-y! position (rect-y region))
-          (matrix4-translate! tmp-matrix position)
-          (matrix4-mult! matrix matrix tmp-matrix)
-          (set-vec2-x! world1 local-x1)
-          (set-vec2-y! world1 local-y1)
-          (set-vec2-x! world2 local-x2)
-          (set-vec2-y! world2 local-y2)
-          (transform! matrix world1)
-          (transform! matrix world2)
+          (if (or rotation scale)
+              (begin
+                (matrix4-identity! matrix)
+                (when rotation
+                  (matrix4-rotate-z! tmp-matrix rotation)
+                  (matrix4-mult! matrix matrix tmp-matrix))
+                (when scale
+                  (matrix4-scale! tmp-matrix scale)
+                  (matrix4-mult! matrix matrix tmp-matrix))
+                (set-vec2-x! position rx)
+                (set-vec2-y! position ry)
+                (matrix4-translate! tmp-matrix position)
+                (matrix4-mult! matrix matrix tmp-matrix)
+                (set-vec2-x! world1 local-x1)
+                (set-vec2-y! world1 local-y1)
+                (set-vec2-x! world2 local-x2)
+                (set-vec2-y! world2 local-y2)
+                (transform! matrix world1)
+                (transform! matrix world2))
+              (begin
+                (set-vec2-x! world1 (+ local-x1 rx))
+                (set-vec2-y! world1 (+ local-y1 ry))
+                (set-vec2-x! world2 (+ local-x2 rx))
+                (set-vec2-y! world2 (+ local-y2 ry))))
           (let ((world-x1 (vec2-x world1))
                 (world-y1 (vec2-y world1))
                 (world-x2 (vec2-x world2))