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Clean up stroke shader

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This commit is contained in:
Grant Sanderson 2024-08-05 15:01:02 -05:00
parent 557819ad03
commit a5926195ee
1 changed files with 35 additions and 32 deletions
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67
manimlib/shaders/quadratic_bezier_stroke/geom.glsl
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@ -87,32 +87,46 @@ vec3 inverse_joint_product(vec3 vect, vec4 joint_product){
}
vec3 step_to_corner(vec3 point, vec3 unit_tan, vec3 unit_normal, vec4 joint_product, bool inner_joint){
vec3 step_to_corner(vec3 point, vec3 tangent, vec3 unit_normal, vec4 joint_product, bool inner_joint){
/*
Step the the left of a curve.
First a perpendicular direction is calculated, then it is adjusted
so as to make a joint.
*/
vec3 unit_tan = normalize(flat_stroke == 0.0 ? project(tangent, unit_normal) : tangent);
vec3 step = normalize(cross(unit_normal, unit_tan));
// Check if an adjustment is needed,
float cos_angle = joint_product.w;
if(inner_joint || int(joint_type) == NO_JOINT || cos_angle > 1 - 1e-5){
return step;
// Check if we can avoid creating a joint
if (inner_joint || int(joint_type) == NO_JOINT) return step;
// Find the appropriate unit joint product
vec4 unit_jp;
if (flat_stroke == 0){
// Figure out what joint product would be for everything projected onto
// the plane perpendicular to the normal direction (which here would be to_camera)
vec3 adj_tan = inverse_joint_product(tangent, joint_product);
adj_tan = project(adj_tan, unit_normal);
unit_jp = normalized_joint_product(get_joint_product(unit_tan, adj_tan));
}else {
unit_jp = normalized_joint_product(joint_product);
}
float cos_angle = unit_jp.w;
if(cos_angle > 1 - 1e-5) return step;
// Adjust based on the joint
float sin_angle = length(joint_product.xyz) * sign(joint_product.z);
float sin_angle = length(unit_jp.xyz) * sign(unit_jp.z);
float shift = (int(joint_type) == MITER_JOINT) ?
(cos_angle + 1.0) / sin_angle :
(cos_angle - 1.0) / sin_angle;
vec3 result = step + shift * unit_tan;
if (length(result) > MITER_LIMIT){
result = MITER_LIMIT * normalize(result);
step = step + shift * unit_tan;
if (length(step) > MITER_LIMIT){
step = MITER_LIMIT * normalize(step);
}
return result;
return step;
}
@ -125,27 +139,16 @@ void emit_point_with_width(
bool inner_joint
){
// Normalize relevant vectors
vec3 unit_tan;
vec4 unit_jp;
vec3 unit_normal;
vec3 to_camera = camera_position - point;
if(flat_stroke == 1.0){
unit_tan = normalize(tangent);
unit_jp = normalized_joint_product(joint_product);
unit_normal = get_joint_unit_normal(joint_product);
}else{
unit_normal = normalize(to_camera);
unit_tan = normalize(project(tangent, unit_normal));
vec3 adj_tan = inverse_joint_product(tangent, joint_product);
adj_tan = project(adj_tan, unit_normal);
unit_jp = normalized_joint_product(get_joint_product(unit_tan, adj_tan));
}
vec3 unit_normal = (flat_stroke == 0.0) ?
normalize(to_camera) :
get_joint_unit_normal(joint_product);
// Choose the "outward" normal direction
if(to_camera.z * dot(unit_normal, to_camera) < 0) unit_normal *= -1;
// Figure out the step from the point to the corners of the
// triangle strip around the polyline
vec3 step = step_to_corner(point, unit_tan, unit_normal, unit_jp, inner_joint);
vec3 step = step_to_corner(point, tangent, unit_normal, joint_product, inner_joint);
// TODO, this gives a somewhat nice effect that's like a ribbon mostly with its
// broad side to the camera. Currently unused by VMobject
@ -159,7 +162,7 @@ void emit_point_with_width(
// Set styling
color = finalize_color(joint_color, point, unit_normal);
if (width == 0) scaled_anti_alias_width = -1.0; // Signal to discard in frag
if (width == 0) scaled_anti_alias_width = -1.0; // Signal to discard in the frag shader
else scaled_anti_alias_width = 2.0 * anti_alias_width * pixel_size / width;
// Emit two corners
@ -202,15 +205,15 @@ void main() {
float stroke_width = mix(v_stroke_width[0], v_stroke_width[2], t);
vec4 color = mix(v_color[0], v_color[2], t);
// Use middle joint product for inner points, flip cross sign for first
vec4 joint_product;
if (i == 0) joint_product = v_joint_product[0] * vec4(-1, -1, -1, 1);
else if (i < n_steps - 1) joint_product = v_joint_product[1];
else joint_product = v_joint_product[2];
// This is sent along to prevent needless joint creation
bool inside_curve = (i > 0 && i < n_steps - 1);
// Use middle joint product for inner points, flip sign for first one's cross product component
vec4 joint_product;
if (i == 0) joint_product = v_joint_product[0] * vec4(-1, -1, -1, 1);
else if (inside_curve) joint_product = v_joint_product[1];
else joint_product = v_joint_product[2];
emit_point_with_width(
point, tangent, joint_product,
stroke_width, color,