Add support for simple periodic sprite animations

1 files changed, 4 insertions, 2 deletions

diff --git a/src/view/util/image.ts b/src/view/util/image.ts
index e01246c..7baeccc 100644
--- a/src/view/util/image.ts
+++ b/src/view/util/image.ts
@@ -14,13 +14,15 @@ export function loadImage(url: string): Promise<HTMLImageElement> {
 export function mkTexture(
 	r: Renderer,
 	src: HTMLCanvasElement|HTMLImageElement,
+	frame: number = 0,
+	total: number = 1,
 ): [WebGLTexture, [number, number], SpriteCoords] {
 	const gl = r.getContext();
 	const texture = gl.createTexture();
 	if (!texture)
 		throw new Error('unable to create texture');
 
-	const w = src.width, h = src.height;
+	const w = src.width, h = src.height / total;
 	const w2 = nextPowerOf2(w), h2 = nextPowerOf2(h);
 
 	const canvas = document.createElement('canvas');
@@ -28,7 +30,7 @@ export function mkTexture(
 	canvas.height = h2;
 
 	const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
-	ctx.drawImage(src, 0, 0);
+	ctx.drawImage(src, 0, frame * h, w, h, 0, 0, w, h);
 
 	gl.bindTexture(gl.TEXTURE_2D, texture);
 	gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, canvas);