fix(particle): texture sheet and gravity bug (#2422)

packages/core/src/particle/ParticleGenerator.ts

@@ -14,6 +14,7 @@ import { SetDataOptions } from "../graphic/enums/SetDataOptions";
 import { VertexAttribute } from "../mesh";
 import { ShaderData } from "../shader";
 import { Buffer } from "./../graphic/Buffer";
+import { ParticleBufferUtils } from "./ParticleBufferUtils";
 import { ParticleRenderer, ParticleUpdateFlags } from "./ParticleRenderer";
 import { ParticleCurveMode } from "./enums/ParticleCurveMode";
 import { ParticleGradientMode } from "./enums/ParticleGradientMode";
@@ -23,12 +24,11 @@ import { ParticleStopMode } from "./enums/ParticleStopMode";
 import { ColorOverLifetimeModule } from "./modules/ColorOverLifetimeModule";
 import { EmissionModule } from "./modules/EmissionModule";
 import { MainModule } from "./modules/MainModule";
+import { ParticleCompositeCurve } from "./modules/ParticleCompositeCurve";
 import { RotationOverLifetimeModule } from "./modules/RotationOverLifetimeModule";
 import { SizeOverLifetimeModule } from "./modules/SizeOverLifetimeModule";
 import { TextureSheetAnimationModule } from "./modules/TextureSheetAnimationModule";
 import { VelocityOverLifetimeModule } from "./modules/VelocityOverLifetimeModule";
-import { ParticleBufferUtils } from "./ParticleBufferUtils";
-import { ParticleCompositeCurve } from "./modules/ParticleCompositeCurve";
 
 /**
  * Particle Generator.
@@ -758,8 +758,16 @@ export class ParticleGenerator {
     // Start speed
     instanceVertices[offset + 18] = startSpeed;
 
-    // Unused, Color, size, rotation,
-    // instanceVertices[offset + 19] = rand.random();
+    // Gravity, unused, size, rotation
+    switch (main.gravityModifier.mode) {
+      case ParticleCurveMode.Constant:
+        instanceVertices[offset + 19] = main.gravityModifier.constant;
+        break;
+      case ParticleCurveMode.TwoConstants:
+        instanceVertices[offset + 19] = main.gravityModifier.evaluate(undefined, main._gravityModifierRand.random());
+        break;
+    }
+
     const colorOverLifetime = this.colorOverLifetime;
     if (colorOverLifetime.enabled && colorOverLifetime.color.mode === ParticleGradientMode.TwoGradients) {
       instanceVertices[offset + 20] = colorOverLifetime._colorGradientRand.random();

packages/core/src/particle/modules/MainModule.ts

@@ -1,4 +1,5 @@
 import { Color, Rand, Vector3, Vector4 } from "@galacean/engine-math";
+import { TransformModifyFlags } from "../../Transform";
 import { deepClone, ignoreClone } from "../../clone/CloneManager";
 import { ICustomClone } from "../../clone/ComponentCloner";
 import { ShaderData } from "../../shader/ShaderData";
@@ -9,7 +10,6 @@ import { ParticleScaleMode } from "../enums/ParticleScaleMode";
 import { ParticleSimulationSpace } from "../enums/ParticleSimulationSpace";
 import { ParticleCompositeCurve } from "./ParticleCompositeCurve";
 import { ParticleCompositeGradient } from "./ParticleCompositeGradient";
-import { TransformModifyFlags } from "../../Transform";
 
 export class MainModule implements ICustomClone {
   private static _tempVector40 = new Vector4();
@@ -96,8 +96,6 @@ export class MainModule implements ICustomClone {
   private _simulationSpace = ParticleSimulationSpace.Local;
   @ignoreClone
   private _generator: ParticleGenerator;
-  @ignoreClone
-  private _gravity = new Vector3();
 
   /**
    * The initial lifetime of particles when emitted.
@@ -322,11 +320,7 @@ export class MainModule implements ICustomClone {
         break;
     }
 
-    const particleGravity = this._gravity;
-    const gravityModifierValue = this.gravityModifier.evaluate(undefined, this._gravityModifierRand.random());
-    Vector3.scale(renderer.scene.physics.gravity, gravityModifierValue, particleGravity);
-
-    shaderData.setVector3(MainModule._gravity, particleGravity);
+    shaderData.setVector3(MainModule._gravity, renderer.scene.physics.gravity);
     shaderData.setInt(MainModule._simulationSpace, this.simulationSpace);
     shaderData.setFloat(MainModule._startRotation3D, +this.startRotation3D);
     shaderData.setInt(MainModule._scaleMode, this.scalingMode);

packages/core/src/shaderlib/extra/particle.vs.glsl

@@ -74,7 +74,7 @@ void main() {
             lifeVelocity = computeParticleLifeVelocity(normalizedAge); 
         #endif
         
-        vec3 gravityVelocity = renderer_Gravity * age;
+        vec3 gravityVelocity = renderer_Gravity * a_Random0.x * age;
 
         vec4 worldRotation;
         if (renderer_SimulationSpace == 0) {

packages/core/src/shaderlib/particle/texture_sheet_animation_module.glsl

@@ -20,7 +20,7 @@ vec2 computeParticleUV(in vec2 uv, in float normalizedAge) {
         float frame = floor(normalizedFrame * renderer_TSATillingParams.z);
 
         float tileRow = frame * renderer_TSATillingParams.x;
-        float floorTotalULength = floor(tileRow);
+        float tileRowIndex = floor(tileRow);
         uv.x += tileRow - tileRowIndex;
         uv.y += tileRowIndex * renderer_TSATillingParams.y;
     #endif