diff --git a/shaders/effects/vwave_crossfade.f.glsl b/shaders/effects/vwave_crossfade.f.glsl index 6f4c36f..dd3075f 100644 --- a/shaders/effects/vwave_crossfade.f.glsl +++ b/shaders/effects/vwave_crossfade.f.glsl @@ -22,8 +22,21 @@ uniform float progress; // effect progress (0..1) in vec2 tex_coord; out vec4 frag_color; -vec3 get_pixel(vec2 xy) { - return mix(texture(old, xy).rgb, texture(tex, xy).rgb, progress); +#define M_PI 3.1415926535897932384626433832795 +#define OLD_PERIOD ((2.0 * M_PI) / 360.0) +#define NEW_PERIOD ((2.0 * M_PI) / 720.0) +#define OLD_SHIFT (-M_PI) +#define NEW_SHIFT (M_PI / 2.0) + +vec3 get_pixel(vec2 old_xy, vec2 new_xy) { + // influence of old color is described by: C_old = (1-t)^2 + // influence of new color increases linearly: C_new = t + // the resulting blend is not normalized + vec3 old = texture(old, old_xy).rgb; + vec3 new = texture(tex, new_xy).rgb; + float old_weight = (1.0 - progress) * (1.0 - progress); + float new_weight = progress; + return (old * old_weight + new * new_weight); } float triangle(float f) { @@ -31,9 +44,14 @@ float triangle(float f) { } void main() { + // old: x = amp * sin((2pi/360)*y + phase + -pi) + // new: x = amp * sin((2pi/720)*y + phase + pi/2) vec2 p = tex_coord * resolution; - float scale = triangle(progress) * 80.0; // (0..0.5..1) -> (0..80..0); - float wobble = progress * 24.0; - float offset = sin((p.y / 100.0) - wobble) * scale; - frag_color = vec4(get_pixel(fract(vec2(p.x + offset, p.y) / resolution)), 1.0); + float amp = triangle(progress) * 80.0; // (0..0.5..1) -> (0..80..0); + float phase = progress * M_PI * 8.0; + float old_off = amp * sin(OLD_PERIOD * p.y + OLD_SHIFT + phase); + float new_off = amp * sin(NEW_PERIOD * p.y + NEW_SHIFT + phase); + vec2 old_xy = fract(vec2(p.x + old_off, p.y) / resolution); + vec2 new_xy = fract(vec2(p.x - new_off, p.y) / resolution); + frag_color = vec4(get_pixel(old_xy, new_xy), 1.0); }