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//
// Vertex shader for rendering a "confetti cannon"
// via a partcle system
//
// Author: Randi Rost
//
// Copyright (c) 2003-2004: 3Dlabs, Inc.
//
// See 3Dlabs-License.txt for license information
//
uniform float Time; // updated each frame by the application
uniform vec4 Background; // constant color equal to background
attribute vec3 Velocity; // initial velocity
attribute float StartTime; // time at which particle is activated
varying vec4 Color;
void main(void)
{
vec4 vert;
float t = Time - StartTime;
if (t >= 0.0)
{
vert = gl_Vertex + vec4 (Velocity * t, 0.0);
vert.y -= 4.9 * t * t;
Color = gl_Color;
}
else
{
vert = gl_Vertex; // Initial position
Color = Background; // "pre-birth" color
}
gl_Position = gl_ModelViewProjectionMatrix * vert;
}
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