Changeset adb104f in opengl-game for explosion.vert

Timestamp:

Jan 10, 2019, 4:38:01 AM (6 years ago)

Author:

Dmitry Portnoy <dmp1488@…>

Branches:

feature/imgui-sdl, master, points-test

Children:

8fbd34f

Parents:

db06984

Message:

Make the explosion shader only emit particles for a short time instead of forever and make it look more like an explosion

File:

• explosion.vert (modified) (2 diffs)

explosion.vert

@@ -1 +1 @@
 #version 410 core
 
-uniform float elapsed_system_time;
+// TODO: Pass the explosion center in as a uniform
+
+uniform float explosion_start_time;
+uniform float cur_time;
 
 layout (location = 0) in vec3 v_i; // initial velocity
@@ -9 +12 @@
 
 void main() {
-   float t = elapsed_system_time - start_time;
-   t = mod(t, 3.0); // allow time to loop around so particle emitter keeps going
+   float duration = 0.5;
+   float t = cur_time - explosion_start_time - start_time;
 
-   vec3 p = vec3(0.0, 0.0, 0.0);
-   vec3 a = vec3(0.0, -1.0, 0.0); // gravity
-   p += v_i * t + 0.5 * a * t * t;
+   if (t < 0.0) {
+      opacity = 0.0;
+   } else {
+      // Need to find out the last time this particle was at the origin
+      // If that is greater than the duration, hide the particle
+      float cur = floor(t / duration);
+      float end = floor((duration - start_time) / duration);
+      if (cur > end) {
+         opacity = 0.0;
+      } else {
+         opacity = 1.0 - (t / duration);
+      }
+   }
 
-   opacity = 1.0 - (t / 3.0);
+   vec3 p = vec3(0.0, 0.0, 0.0); //  this is the center of the explosion
+   vec3 a = vec3(0.0, 0.1, 0.0);
+   p += normalize(v_i) * mod(t, duration) / duration * 0.3; // allow time to loop around so particle emitter keeps going
 
    gl_Position = vec4(p, 1.0);