Some work to make particle shader able to render billboard

The lifetime in height map stimulation will always now < 1.0f

data/shaders/alphatest_particle.vert

@@ -3,8 +3,8 @@ uniform int flips;
 #ifdef Explicit_Attrib_Location_Usable
 
 layout(location = 0) in vec3 Position;
-layout(location = 1) in vec4 mixed_color;
+layout(location = 1) in vec4 color_lifetime;
-layout(location = 2) in vec2 lifetime_and_size;
+layout(location = 2) in vec2 size;
 
 layout(location = 3) in vec2 Texcoord;
 layout(location = 4) in vec2 quadcorner;
@@ -13,8 +13,8 @@ layout(location = 6) in float anglespeed;
 #else
 
 in vec3 Position;
-in vec4 mixed_color;
+in vec4 color_lifetime;
-in vec2 lifetime_and_size;
+in vec2 size;
 
 in vec2 Texcoord;
 in vec2 quadcorner;
@@ -27,24 +27,30 @@ out vec4 pc;
 
 void main(void)
 {
-    if (lifetime_and_size.y == 0.0)
+    if (size.x == 0.0 && size.y == 0.0)
     {
         gl_Position = vec4(0.);
+        pc = vec4(0.0);
+        tc = vec2(0.0);
         return;
     }
+
+    float lifetime = color_lifetime.w;
+    pc = vec4(color_lifetime.zyx, 1.0);
     tc = Texcoord;
-    pc = mixed_color.zyxw;
+
 #if !defined(sRGB_Framebuffer_Usable) && !defined(Advanced_Lighting_Enabled)
     pc.rgb = pow(pc.rgb, vec3(1.0 / 2.2));
 #endif
+
     vec4 viewpos = vec4(0.);
     if (flips == 1)
     {
-        float angle = lifetime_and_size.x * anglespeed;
+        float angle = lifetime * anglespeed;
         float sin_a = sin(mod(angle / 2.0, 6.283185307179586));
         float cos_a = cos(mod(angle / 2.0, 6.283185307179586));
         vec4 quat = normalize(vec4(vec3(0.0, 1.0, 0.0) * sin_a, cos_a));
-        vec3 newquadcorner = lifetime_and_size.y * vec3(quadcorner, 0.);
+        vec3 newquadcorner = vec3(size * quadcorner, 0.0);
         newquadcorner = newquadcorner + 2.0 * cross(cross(newquadcorner,
             quat.xyz) + quat.w * newquadcorner, quat.xyz);
         viewpos = ViewMatrix * vec4(Position + newquadcorner, 1.0);
@@ -52,7 +58,7 @@ void main(void)
     else
     {
         viewpos = ViewMatrix * vec4(Position, 1.0);
-        viewpos += lifetime_and_size.y * vec4(quadcorner, 0., 0.);
+        viewpos += vec4(size * quadcorner, 0.0, 0.0);
     }
     gl_Position = ProjectionMatrix * viewpos;
 }

data/shaders/simple_particle.vert

@@ -3,8 +3,8 @@ uniform int flips;
 #ifdef Explicit_Attrib_Location_Usable
 
 layout(location = 0) in vec3 Position;
-layout(location = 1) in vec4 mixed_color;
+layout(location = 1) in vec4 color_lifetime;
-layout(location = 2) in vec2 lifetime_and_size;
+layout(location = 2) in vec2 size;
 
 layout(location = 3) in vec2 Texcoord;
 layout(location = 4) in vec2 quadcorner;
@@ -13,8 +13,8 @@ layout(location = 6) in float anglespeed;
 #else
 
 in vec3 Position;
-in vec4 mixed_color;
+in vec4 color_lifetime;
-in vec2 lifetime_and_size;
+in vec2 size;
 
 in vec2 Texcoord;
 in vec2 quadcorner;
@@ -27,24 +27,30 @@ out vec4 pc;
 
 void main(void)
 {
-    if (lifetime_and_size.y == 0.0)
+    if (size.x == 0.0 && size.y == 0.0)
     {
         gl_Position = vec4(0.);
+        pc = vec4(0.0);
+        tc = vec2(0.0);
         return;
     }
+
+    float lifetime = color_lifetime.w;
+    pc = vec4(color_lifetime.zyx, 1.0) * smoothstep(1.0, 0.8, lifetime);
     tc = Texcoord;
-    pc = mixed_color.zyxw * smoothstep(1.0, 0.8, lifetime_and_size.x);
+
 #if !defined(sRGB_Framebuffer_Usable) && !defined(Advanced_Lighting_Enabled)
     pc.rgb = pow(pc.rgb, vec3(1.0 / 2.2));
 #endif
+
     vec4 viewpos = vec4(0.);
     if (flips == 1)
     {
-        float angle = lifetime_and_size.x * anglespeed;
+        float angle = lifetime * anglespeed;
         float sin_a = sin(mod(angle / 2.0, 6.283185307179586));
         float cos_a = cos(mod(angle / 2.0, 6.283185307179586));
         vec4 quat = normalize(vec4(vec3(0.0, 1.0, 0.0) * sin_a, cos_a));
-        vec3 newquadcorner = lifetime_and_size.y * vec3(quadcorner, 0.);
+        vec3 newquadcorner = vec3(size * quadcorner, 0.0);
         newquadcorner = newquadcorner + 2.0 * cross(cross(newquadcorner,
             quat.xyz) + quat.w * newquadcorner, quat.xyz);
         viewpos = ViewMatrix * vec4(Position + newquadcorner, 1.0);
@@ -52,7 +58,7 @@ void main(void)
     else
     {
         viewpos = ViewMatrix * vec4(Position, 1.0);
-        viewpos += lifetime_and_size.y * vec4(quadcorner, 0., 0.);
+        viewpos += vec4(size * quadcorner, 0.0, 0.0);
     }
     gl_Position = ProjectionMatrix * viewpos;
 }

src/graphics/cpu_particle_manager.hpp

@@ -40,20 +40,21 @@ using namespace irr;
 struct CPUParticle
 {
     core::vector3df m_position;
-    video::SColor m_mixed_color;
+    video::SColor m_color_lifetime;
-    short m_lifetime_and_size[2];
+    short m_size[2];
     // ------------------------------------------------------------------------
     CPUParticle(const core::vector3df& position,
                 const core::vector3df& color_from,
-                const core::vector3df& color_to, float lifetime, float size)
+                const core::vector3df& color_to, float lf_time, float size)
-         : m_position(position), m_mixed_color(-1)
+         : m_position(position)
     {
-        core::vector3df ret = color_from + (color_to - color_from) * lifetime;
+        core::vector3df ret = color_from + (color_to - color_from) * lf_time;
-        m_mixed_color.setRed(core::clamp((int)(ret.X * 255.0f), 0, 255));
+        m_color_lifetime.setRed(core::clamp((int)(ret.X * 255.0f), 0, 255));
-        m_mixed_color.setBlue(core::clamp((int)(ret.Y * 255.0f), 0, 255));
+        m_color_lifetime.setBlue(core::clamp((int)(ret.Y * 255.0f), 0, 255));
-        m_mixed_color.setGreen(core::clamp((int)(ret.Z * 255.0f), 0, 255));
+        m_color_lifetime.setGreen(core::clamp((int)(ret.Z * 255.0f), 0, 255));
-        m_lifetime_and_size[0] = MiniGLM::toFloat16(lifetime);
+        m_color_lifetime.setAlpha(core::clamp((int)(lf_time * 255.0f), 0, 255));
-        m_lifetime_and_size[1] = MiniGLM::toFloat16(size);
+        m_size[0] = MiniGLM::toFloat16(size);
+        m_size[1] = m_size[0];
     }
 };
 

src/graphics/shader.cpp

@@ -163,8 +163,8 @@ void ShaderBase::setAttribute(AttributeType type)
         break;
     case PARTICLES_RENDERING:
         glBindAttribLocation(m_program, 0, "Position");
-        glBindAttribLocation(m_program, 1, "mixed_color");
+        glBindAttribLocation(m_program, 1, "color_lifetime");
-        glBindAttribLocation(m_program, 2, "lifetime_and_size");
+        glBindAttribLocation(m_program, 2, "size");
         glBindAttribLocation(m_program, 3, "Texcoord");
         glBindAttribLocation(m_program, 4, "quadcorner");
         glBindAttribLocation(m_program, 5, "rotationvec");

src/graphics/stk_particle.cpp

@@ -333,8 +333,8 @@ void STKParticle::stimulateHeightMap(float dt, unsigned int active_count,
         core::vector3df adjusted_initial_direction =
             initial_new_position - initial_position;
         float adjusted_lifetime = lifetime + (dt / lifetime_initial);
-        reset = reset || ((adjusted_lifetime > 1.0f) && (i <= active_count));
+        reset = reset || adjusted_lifetime > 1.0f;
-        reset = reset || (lifetime < 0.0f);
+        reset = reset || lifetime < 0.0f;
 
         new_particle_position = !reset ?
             (particle_position + particle_direction * dt) : initial_position;