radial stim generation in shaders;

src/visual/GratingStim.js

@@ -26,6 +26,7 @@ import gaussShader from "./shaders/gaussShader.frag";
 import crossShader from "./shaders/crossShader.frag";
 import radRampShader from "./shaders/radRampShader.frag";
 import raisedCosShader from "./shaders/raisedCosShader.frag";
+import radialStim from "./shaders/radialShader.frag";
 
 /**
  * Grating Stimulus.
@@ -263,6 +264,15 @@ export class GratingStim extends VisualStim
 				uColor: [1., 1., 1.],
 				uAlpha: 1.0
 			}
+		},
+		radialStim: {
+			shader: radialStim,
+			uniforms: {
+				uFreq: 20.0,
+				uPhase: 0.0,
+				uColor: [1., 1., 1.],
+				uAlpha: 1.0
+			}
 		}
 	};
 
@@ -742,7 +752,8 @@ export class GratingStim extends VisualStim
 					const maskMesh = this._getPixiMeshFromPredefinedShaders(this._mask);
 					const rt = PIXI.RenderTexture.create({
 						width: this._size_px[0],
-						height: this._size_px[1]
+						height: this._size_px[1],
+						scaleMode: this._interpolate ? PIXI.SCALE_MODES.LINEAR : PIXI.SCALE_MODES.NEAREST
 					});
 					this.win._renderer.render(maskMesh, {
 						renderTexture: rt

src/visual/shaders/radialShader.frag

@@ -0,0 +1,36 @@
+/**
+ * Radial grating.
+ *
+ * @author Nikita Agafonov
+ * @copyright (c) 2020-2022 Open Science Tools Ltd. (https://opensciencetools.org)
+ * @license Distributed under the terms of the MIT License
+ * @description Creates 2d radial grating image. Based on https://www.shadertoy.com/view/wtjGzt
+ * @usedby GratingStim.js
+ */
+
+#version 300 es
+precision mediump float;
+
+in vec2 vUvs;
+out vec4 shaderOut;
+uniform float uFreq;
+uniform float uPhase;
+uniform vec3 uColor;
+uniform float uAlpha;
+
+#define M_PI 3.14159265358979
+#define PI2 2.* M_PI
+
+float aastep(float x) {     // --- antialiased step(.5)
+    float w = fwidth(x);    // pixel width. NB: x must not be discontinuous or factor discont out
+    return smoothstep(.7,-.7,(abs(fract(x-.25)-.5)-.25)/w); // just use (offseted) smooth squares
+}
+
+void main() {
+    vec2 uv = vUvs * 2. - 1.;
+    // converting first to [-1, 1] space to get the proper color functionality
+    // then back to [0, 1]
+    float v = uFreq * atan(uv.y, uv.x) / 6.28;
+    float s = aastep(v) * 2. - 1.;
+    shaderOut = vec4(vec3(s) * uColor * .5 + .5, 1.0) * uAlpha;
+}