Did rain splash

Author: Cheng Xie

src/common.h

@@ -55,4 +55,8 @@ inline float randf(float a, float b) {
     return randf() * (b - a) + a; 
 }
 
+inline float linear_interpolate(float a, float b, float ratio) {
+    return a * (1 - ratio) + b * ratio;
+}
+
 #endif // COMMON_H

src/final.pro

@@ -49,7 +49,8 @@ SOURCES += main.cpp \
     terrainmaterial.cpp \
     material.cpp \
     cloud.cpp \
-    rain.cpp
+    rain.cpp \
+    rainsplash.cpp
 
 HEADERS += mainwindow.h \
     view.h \
@@ -87,6 +88,7 @@ HEADERS += mainwindow.h \
     DustcloudParticleSystem.h \
     terrainmaterial.h \
     cloud.h \
-    rain.h
+    rain.h \
+    rainsplash.h
 
 FORMS += mainwindow.ui

src/particlematerial.cpp

@@ -27,12 +27,14 @@ void ParticleMaterial::apply(DrawContext &context)
 
     //glDisable(GL_DEPTH_TEST);
     glDepthMask(GL_FALSE);
+    glDisable(GL_CULL_FACE);
 }
 
 void ParticleMaterial::endRender()
 {
     //glEnable(GL_DEPTH_TEST);
     glDepthMask(GL_TRUE);
+    glEnable(GL_CULL_FACE);
 }
 
 void ParticleMaterial::setTexture(Texture *texture)

src/rain.cpp

@@ -12,12 +12,12 @@ Rain::Rain(float radius)
     Texture* texture =  TextureCache::getInstance()->acquire("rain", TextureType::Texture2D);
     setParticleTexture(texture);
 
-    setEmissionRate(400);
+    setEmissionRate(1000);
 
     setMaxParticleCount(10000);
 
     ParticleMaterial* material = static_cast<ParticleMaterial *>(material_);
-    material->setLengthScale(8);
+    material->setLengthScale(12);
 }
 
 void Rain::spawnParticle(Particle *particle)
@@ -39,7 +39,7 @@ void Rain::spawnParticle(Particle *particle)
 
     particle->maxLife = 2;
 
-    particle->size = 0.07;
+    particle->size = 0.08;
 
     float scale = randf(0.6f, 0.8f);
     particle->color = {scale, scale, scale};

src/rainsplash.cpp

@@ -0,0 +1,60 @@
+#include "rainsplash.h"
+#include "texture.h"
+#include "texturecache.h"
+#include "particlematerial.h"
+#include "terrain.h"
+
+RainSplash::RainSplash(float radius, bool mist, Terrain* terrain)
+{
+    radius_ = radius;
+    terrain_ = terrain;
+    
+    Texture* texture = NULL;
+    ParticleMaterial* material = static_cast<ParticleMaterial *>(material_);
+    
+    if (mist) {
+        texture = TextureCache::getInstance()->acquire("rainmist", TextureType::Texture2D);
+        material->setHorizontal(false);
+    }
+    else {
+        texture = TextureCache::getInstance()->acquire("raindrop", TextureType::Texture2D);
+        material->setHorizontal(true);
+    }
+
+    setParticleTexture(texture);
+    
+    setEmissionRate(1000);
+    
+    setMaxParticleCount(10000);
+}
+
+void RainSplash::spawnParticle(Particle *particle)
+{
+    float phi = randf(0, M_PI * 2);
+    float r = radius_ * randf(0.3, 1.0);
+    
+    float x = cosf(phi) * r;
+    float z = sinf(phi) * r;
+    float y = terrain_->height(x, z) + 0.1;
+   
+    particle->position = {x, y, z};
+    
+    particle->maxLife = randf(0.4, 0.6);
+    
+    particle->size = startSize_ = randf(0.2, 0.3);
+    
+    float c = randf(0.6, 0.9);
+    particle->color = {c, c, c};
+    
+    particle->opacity = startOpacity_ = randf(0.6, 0.8);
+    
+    startSize_ = 0.2;
+}
+
+void RainSplash::updateParticle(Particle &particle, float dt)
+{
+    float x = particle.life / particle.maxLife;
+    particle.size = linear_interpolate(startSize_, startSize_ + 0.15, x);
+    particle.opacity = startOpacity_ * (1 - x);
+    
+}

src/rainsplash.h

@@ -0,0 +1,27 @@
+#ifndef RAINSPLASH_H
+#define RAINSPLASH_H
+
+#include "particlesystem.h"
+
+class Terrain;
+
+class RainSplash : public ParticleSystem
+{
+public:
+    RainSplash(float radius, bool mist, Terrain* terrain);
+    
+    virtual void spawnParticle(Particle *particle) override;
+    
+    virtual void updateParticle(Particle &particle, float dt) override;
+    
+private:
+    float radius_ = 0;
+    
+    // weak reference
+    Terrain* terrain_ = NULL;
+    
+    float startSize_ = 0;
+    float startOpacity_ = 0;
+};
+
+#endif // RAINSPLASH_H

src/scene.cpp

@@ -13,6 +13,7 @@
 #include "terrain.h"
 #include "cloud.h"
 #include "rain.h"
+#include "rainsplash.h"
 
 Scene::Scene()
 {
@@ -93,6 +94,13 @@ void Scene::initialize()
     // Rain
     Rain* rain = new Rain(30);
     sceneObjects_.push_back(rain);
+    
+    // RainSplash
+    RainSplash* splash = new RainSplash(50, true, terrain);
+    sceneObjects_.push_back(splash);
+    
+    splash = new RainSplash(50, false, terrain);
+    sceneObjects_.push_back(splash);
 }
 
 void Scene::render(DrawContext &context)