update sim to dynamic time-step

Signed-off-by: Guilherme Avila <[email protected]>

Author: sciecode

src/glsl/integrate.frag.js

@@ -3,15 +3,14 @@ precision highp float;
 precision highp sampler2D;
 
 uniform vec2 tSize;
+uniform float dt;
 uniform float order;
 uniform sampler2D tOriginal;
 uniform sampler2D tPrevious0;
 uniform sampler2D tPrevious1;
 uniform sampler2D tPosition0;
 uniform sampler2D tPosition1;
 
-#define dt2 0.000256
-
 vec3 unpackPosition( vec3 pos ) {
 
 	pos *= 1024.0;
@@ -22,13 +21,15 @@ vec3 unpackPosition( vec3 pos ) {
 
 void main() {
 
+	float dt2 = dt*dt;
+
 	vec2 uv = gl_FragCoord.xy / tSize.xy;
 
 	vec3 org = texture2D( tOriginal, uv ).xyz;
 	vec3 prv = ( texture2D( tPrevious0, uv ).xyz + texture2D( tPrevious1, uv ).xyz ) / 1024.0;
 	vec3 pos = ( texture2D( tPosition0, uv ).xyz + texture2D( tPosition1, uv ).xyz ) / 1024.0;
 
-	vec3 offset = ( org - pos ) * 18.5 * dt2 * 8.33333;
+	vec3 offset = ( org - pos ) * 260.5 * dt2;
 	vec3 disp = ( pos - prv ) * 0.94 + pos;
 
 	gl_FragColor = vec4( unpackPosition( disp + offset ), 1.0 );

src/modules/fbo.js

@@ -14,7 +14,7 @@ RESOLUTION,
 renderer, mesh, targetRT, normalsRT,
 originalRT, previousRT, positionRT,
 adjacentsRT, distancesRT,
-steps = 40;
+steps = 40, prevTime, dt;
 
 
 const
@@ -73,6 +73,8 @@ function init( WebGLRenderer ) {
 
 	}
 
+	prevTime = performance.now();
+
 }
 
 function copyTexture( input, output, order ) {
@@ -183,12 +185,15 @@ function integrate() {
 
 	mesh.material = integrateShader;
 	integrateShader.uniforms.tSize.value = tSize;
+	integrateShader.uniforms.dt.value = dt;
 	integrateShader.uniforms.tOriginal.value = originalRT.texture;
 	integrateShader.uniforms.tPrevious0.value = previousRT[ 0 ].texture;
 	integrateShader.uniforms.tPrevious1.value = previousRT[ 1 ].texture;
 	integrateShader.uniforms.tPosition0.value = positionRT[ 0 ].texture;
 	integrateShader.uniforms.tPosition1.value = positionRT[ 1 ].texture;
 
+	// console.log(dt);
+
 	// integer-part
 	integrateShader.uniforms.order.value = 1;
 	renderer.setRenderTarget( targetRT[ 0 ] );
@@ -294,6 +299,10 @@ function computeVertexNormals( ) {
 
 function update() {
 
+	const now = performance.now();
+	dt = (now - prevTime)/1000;
+	prevTime = now;
+
 	integrate();
 
 	let mouseUpdating = MOUSE.updating();
@@ -310,4 +319,8 @@ function update() {
 
 }
 
+window.onfocus = function() {
+	prevTime = performance.now();
+}
+
 export { init, update, positionRT, normalsRT };