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graphics: fixup aa line rasterizer

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This commit is contained in:
K. Lange 2021-10-04 15:04:34 +09:00
parent fbd84d1609
commit b87381116b
2 changed files with 20 additions and 9 deletions
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1
base/usr/include/toaru/graphics.h
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@ -115,6 +115,7 @@ extern float gfx_point_dot(const struct gfx_point * a, const struct gfx_point *
extern struct gfx_point gfx_point_sub(const struct gfx_point * a, const struct gfx_point * b);
extern struct gfx_point gfx_point_add(const struct gfx_point * a, const struct gfx_point * b);
extern float gfx_line_distance(const struct gfx_point * p, const struct gfx_point * v, const struct gfx_point * w);
extern void draw_line_aa_points(gfx_context_t * ctx, struct gfx_point *v, struct gfx_point *w, uint32_t color, float thickness);
extern void draw_line_aa(gfx_context_t * ctx, int x_1, int x_2, int y_1, int y_2, uint32_t color, float thickness);
struct gradient_definition {

40
lib/graphics.c
View File

@ -1143,23 +1143,33 @@ float gfx_line_distance(const struct gfx_point * p, const struct gfx_point * v,
*
* Maybe acceptable for baked UI elements?
*/
void draw_line_aa_points(gfx_context_t * ctx, struct gfx_point *v, struct gfx_point *w, uint32_t color, float thickness) {
/* Calculate viable bounds */
int x_0 = max(min(v->x - thickness - 1, w->x - thickness - 1), 0);
int x_1 = min(max(v->x + thickness + 1, w->x + thickness + 1), ctx->width);
int y_0 = max(min(v->y - thickness - 1, w->y - thickness - 1), 0);
int y_1 = min(max(v->y + thickness + 1, w->y + thickness + 1), ctx->height);
for (int y = y_0; y < y_1; ++y) {
for (int x = x_0; x < x_1; ++x) {
struct gfx_point p = {x,y};
float d = gfx_line_distance(&p,v,w);
if (d < thickness + 0.5) {
if (d < thickness - 0.5) {
GFX(ctx,x,y) = alpha_blend_rgba(GFX(ctx,x,y), color);
} else {
float alpha = 1.0 - (d - thickness + 0.5);
GFX(ctx,x,y) = alpha_blend_rgba(GFX(ctx,x,y), premultiply(rgba(_RED(color),_GRE(color),_BLU(color),(int)((double)_ALP(color) * alpha))));
}
}
}
}
}
void draw_line_aa(gfx_context_t * ctx, int x_1, int x_2, int y_1, int y_2, uint32_t color, float thickness) {
struct gfx_point v = {(float)x_1, (float)y_1};
struct gfx_point w = {(float)x_2, (float)y_2};
for (int y = 0; y < ctx->height; ++y) {
for (int x = 0; x < ctx->width; ++x) {
struct gfx_point p = {x,y};
float d = gfx_line_distance(&p,&v,&w);
if (d < thickness + 0.5) {
if (d < thickness - 0.5) {
GFX(ctx,x,y) = color;
} else {
uint32_t f_color = rgb(255 * (1.0 - (d - thickness + 0.5)), 0, 0);
GFX(ctx,x,y) = alpha_blend(GFX(ctx,x,y), color, f_color);
}
}
}
}
draw_line_aa_points(ctx,&v,&w,color,thickness);
}