From a1913661e795ce3d2597824a30ac1eaa9aeeb8bd Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Fri, 2 Dec 2016 17:48:19 +0100
Subject: [PATCH] add Camera function
---
transform.go | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/transform.go b/transform.go
index 5e96fab..01b183b 100644
--- a/transform.go
+++ b/transform.go
@@ -27,6 +27,12 @@ func Position(position Vec) Transform {
}
}
+// Position sets position.
+func (t Transform) Position(position Vec) Transform {
+ t.pos = position
+ return t
+}
+
// Move adds delta to position.
func (t Transform) Move(delta Vec) Transform {
t.pos += delta
@@ -50,7 +56,7 @@ func (t Transform) MoveAnchor(delta Vec) Transform {
// Note, that subsequent calls to this method accumulate the final scale factor. Scaling two times by 2 is equivalent
// to scaling once by 4.
func (t Transform) Scale(scale float64) Transform {
- t.sca *= V(scale, scale)
+ t.sca = t.sca.Scaled(scale)
return t
}
@@ -59,7 +65,7 @@ func (t Transform) Scale(scale float64) Transform {
// Note, that subsequent calls to this method accumulate the final scale factor. Scaling two times by 2 is equivalent
// to scaling once by 4.
func (t Transform) ScaleXY(scale Vec) Transform {
- t.sca *= scale
+ t.sca = V(t.sca.X()*scale.X(), t.sca.Y()*scale.Y())
return t
}
@@ -81,3 +87,13 @@ func (t Transform) Mat3() mgl32.Mat3 {
mat = mat.Mul3(mgl32.Translate2D(float32(t.anc.X()), float32(t.anc.Y())))
return mat
}
+
+// Camera is a convenience function, that returns a Transform that acts like a camera.
+// Center is the position in the world coordinates, that will be projected onto the center of the screen.
+// One unit in world coordinates will be projected onto zoom pixels.
+//
+// It is possible to apply additional rotations, scales and moves to the returned transform.
+func Camera(center, zoom, screenSize Vec) Transform {
+ scale := screenSize * zoom / 2
+ return Position(0).Anchor(center).ScaleXY(scale)
+}
--
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