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Reduced memory transfer of OpenGL gradient uniform upload. Rearranged gradient uniforms on OpenGL side to be more performant.

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This commit is contained in:
shan 2022-10-05 16:07:43 -07:00
parent f7ce7244d0
commit 1eb8d972ba
7 changed files with 83 additions and 128 deletions
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43
glow/src/shader/common/gradient.frag
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@ -1,6 +1,3 @@
// GLSL does not support dynamically sized arrays without SSBOs
#define MAX_STOPS 64
#ifdef GL_ES
#ifdef GL_FRAGMENT_PRECISION_HIGH
precision highp float;
@ -16,34 +13,38 @@ layout (location = 0) out vec4 fragColor;
in vec2 raw_position;
uniform vec2 gradient_start;
uniform vec2 gradient_end;
uniform vec4 gradient_direction;
uniform uint color_stops_size;
uniform float color_stop_offsets[MAX_STOPS];
uniform vec4 color_stop_colors[MAX_STOPS];
// GLSL does not support dynamically sized arrays without SSBOs so this is capped to 16 stops
//stored as color(vec4) -> offset(vec4) sequentially;
uniform vec4 color_stops[32];
//TODO: rewrite without branching to make ALUs happy
void main() {
vec2 gradient_vec = vec2(gradient_end - gradient_start);
vec2 current_vec = vec2(raw_position.xy - gradient_start);
vec2 start = gradient_direction.xy;
vec2 end = gradient_direction.zw;
vec2 gradient_vec = vec2(end - start);
vec2 current_vec = vec2(raw_position.xy - start);
vec2 unit = normalize(gradient_vec);
float coord_offset = dot(unit, current_vec) / length(gradient_vec);
for (uint i = 0; i < color_stops_size - 1; i++) {
float stop_offset = color_stop_offsets[i];
float next_stop_offset = color_stop_offsets[i + 1];
for (uint i = 0; i < color_stops_size - 2; i += 2) {
vec4 color = color_stops[i];
float offset = color_stops[i+1].x;
if (stop_offset <= coord_offset && coord_offset <= next_stop_offset) {
fragColor = mix(color_stop_colors[i], color_stop_colors[i+1], smoothstep(
stop_offset,
next_stop_offset,
vec4 next_color = color_stops[i+2];
float next_offset = color_stops[i+3].x;
if (offset <= coord_offset && coord_offset <= next_offset) {
fragColor = mix(color, next_color, smoothstep(
offset,
next_offset,
coord_offset
));
} else if (coord_offset < color_stop_offsets[0]) {
fragColor = color_stop_colors[0];
} else if (coord_offset > color_stop_offsets[color_stops_size - 1]) {
fragColor = color_stop_colors[color_stops_size - 1];
} else if (coord_offset < color_stops[1].x) {
fragColor = color_stops[0];
} else if (coord_offset > color_stops[color_stops_size - 1].x) {
fragColor = color_stops[color_stops_size - 2];
}
}
}