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Small clean up

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This commit is contained in:
Grant Sanderson
2023-01-18 13:07:18 -08:00
parent e20efda3df
commit 13c41be17f
1 changed files with 9 additions and 7 deletions
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16
manimlib/shaders/quadratic_bezier_stroke/frag.glsl
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@ -12,18 +12,21 @@ out vec4 frag_color;
const float QUICK_DIST_WIDTH = 0.2; const float QUICK_DIST_WIDTH = 0.2;
// Distance from (x0, y0) to the curve y = x^2 float dist_to_curve(){
float dist_to_curve(float x0, float y0){ // Returns distance from uv_coords to the curve v = u^2
float x0 = uv_coords.x;
float y0 = uv_coords.y;
// In the linear case, the curve will have // In the linear case, the curve will have
// been set to equal the x axis // been set to equal the x axis
if(bool(is_linear)) return y0; if(bool(is_linear)) return abs(y0);
if(uv_stroke_width < QUICK_DIST_WIDTH){ if(uv_stroke_width < QUICK_DIST_WIDTH){
// This is a quick approximation for computing // This is a quick approximation for computing
// the distance to the curve. // the distance to the curve.
// Evaluate F(x, y) = y - x^2 // Evaluate F(x, y) = y - x^2
// divide by its gradient's magnitude // divide by its gradient's magnitude
return (y0 - x0 * x0) / sqrt(1 + 4 * x0 * x0); return abs((y0 - x0 * x0) / sqrt(1 + 4 * x0 * x0));
} }
// Otherwise, solve for the minimal distance. // Otherwise, solve for the minimal distance.
// The distance squared between (x0, y0) and a point (x, x^2) looks like // The distance squared between (x0, y0) and a point (x, x^2) looks like
@ -50,9 +53,8 @@ float dist_to_curve(float x0, float y0){
void main() { void main() {
if (uv_stroke_width == 0) discard; if (uv_stroke_width == 0) discard;
// Compute sdf for the region around the curve we wish to color. // sdf for the region around the curve we wish to color.
float dist = dist_to_curve(uv_coords.x, uv_coords.y); float signed_dist = dist_to_curve() - 0.5 * uv_stroke_width;
float signed_dist = abs(dist) - 0.5 * uv_stroke_width;
frag_color = color; frag_color = color;
frag_color.a *= smoothstep(0.5, -0.5, signed_dist / uv_anti_alias_width); frag_color.a *= smoothstep(0.5, -0.5, signed_dist / uv_anti_alias_width);