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Webgl points renderer / use a smaller canvas for hit detection render

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The hit detection render is now done against a canvas with half the
width/height of the main render. This still provides sufficient precision
while requiring a much smaller memory allocation (especially for
retina devices).
This commit is contained in:
Olivier Guyot
2019-10-31 13:40:51 +01:00
parent 43010c8934
commit 600e1a4647
2 changed files with 7 additions and 3 deletions
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7
src/ol/renderer/webgl/PointsLayer.js
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@@ -503,7 +503,7 @@ class WebGLPointsLayerRenderer extends WebGLLayerRenderer {
const pixel = applyTransform(frameState.coordinateToPixelTransform, coordinate.slice());
const data = this.hitRenderTarget_.readPixel(pixel[0], pixel[1]);
const data = this.hitRenderTarget_.readPixel(pixel[0] / 2, pixel[1] / 2);
const color = [
data[0] / 255,
data[1] / 255,
@@ -531,7 +531,10 @@ class WebGLPointsLayerRenderer extends WebGLLayerRenderer {
return;
}
this.hitRenderTarget_.setSize(frameState.size);
this.hitRenderTarget_.setSize([
Math.floor(frameState.size[0] / 2),
Math.floor(frameState.size[1] / 2)
]);
this.helper.useProgram(this.hitProgram_);
this.helper.prepareDrawToRenderTarget(frameState, this.hitRenderTarget_, true);

3
src/ol/webgl/Helper.js
View File

@@ -456,9 +456,10 @@ class WebGLHelper extends Disposable {
*/
prepareDrawToRenderTarget(frameState, renderTarget, opt_disableAlphaBlend) {
const gl = this.getGL();
const size = renderTarget.getSize();
gl.bindFramebuffer(gl.FRAMEBUFFER, renderTarget.getFramebuffer());
gl.viewport(0, 0, frameState.size[0], frameState.size[1]);
gl.viewport(0, 0, size[0], size[1]);
gl.bindTexture(gl.TEXTURE_2D, renderTarget.getTexture());
gl.clearColor(0.0, 0.0, 0.0, 0.0);
gl.clear(gl.COLOR_BUFFER_BIT);