Merge pull request #80638 from sepTN/fix-particle-shader-rand

Fix particle shader deterministic random values

scene/resources/particle_process_material.cpp

@@ -683,11 +683,13 @@ void ParticleProcessMaterial::_update_shader() {
 		code += "	pos.z = 0.0;\n";
 	}
 	code += "	// apply linear acceleration\n";
-	code += "	force += length(VELOCITY) > 0.0 ? normalize(VELOCITY) * tex_linear_accel * mix(linear_accel_min, linear_accel_max, rand_from_seed(alt_seed)) : vec3(0.0);\n";
+	code += "	float linear_accel_rand = rand_from_seed(alt_seed);\n";
+	code += "	force += length(VELOCITY) > 0.0 ? normalize(VELOCITY) * tex_linear_accel * mix(linear_accel_min, linear_accel_max, linear_accel_rand) : vec3(0.0);\n";
 	code += "	// apply radial acceleration\n";
 	code += "	vec3 org = EMISSION_TRANSFORM[3].xyz;\n";
 	code += "	vec3 diff = pos - org;\n";
-	code += "	force += length(diff) > 0.0 ? normalize(diff) * tex_radial_accel * mix(radial_accel_min, radial_accel_max, rand_from_seed(alt_seed)) : vec3(0.0);\n";
+	code += "	float radial_accel_rand = rand_from_seed(alt_seed);\n";
+	code += "	force += length(diff) > 0.0 ? normalize(diff) * tex_radial_accel * mix(radial_accel_min, radial_accel_max, radial_accel_rand) : vec3(0.0);\n";
 	code += "	// apply tangential acceleration;\n";
 	code += "	float tangent_accel_val = tex_tangent_accel * mix(tangent_accel_min, tangent_accel_max, rand_from_seed(alt_seed));\n";
 	if (particle_flags[PARTICLE_FLAG_DISABLE_Z]) {