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Experimental slow sprite rotation

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This commit is contained in:
K. Lange 2018-09-17 20:35:40 +09:00
parent 703253a8e8
commit 0c4bd30242
2 changed files with 55 additions and 0 deletions
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2
base/usr/include/toaru/graphics.h
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@ -106,3 +106,5 @@ extern struct gfx_point gfx_point_sub(struct gfx_point * a, struct gfx_point * b
extern struct gfx_point gfx_point_add(struct gfx_point * a, struct gfx_point * b);
extern float gfx_line_distance(struct gfx_point * p, struct gfx_point * v, struct gfx_point * w);
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);
extern void draw_sprite_rotate(gfx_context_t * ctx, sprite_t * sprite, int32_t x, int32_t y, float rotation, float alpha);

53
lib/graphics.c
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@ -635,6 +635,8 @@ uint32_t getBilinearFilteredPixelColor(sprite_t * tex, double u, double v) {
int y = floor(v);
if (x >= tex->width) return 0;
if (y >= tex->height) return 0;
if (x <= 0) return 0;
if (y <= 0) return 0;
double u_ratio = u - x;
double v_ratio = v - y;
double u_o = 1 - u_ratio;
@ -867,3 +869,54 @@ void draw_line_aa(gfx_context_t * ctx, int x_1, int x_2, int y_1, int y_2, uint3
}
}
}
static void calc_rotation(double x, double y, double px, double py, double rotation, double * u, double * v) {
double s = sin(rotation);
double c = cos(rotation);
/* Translate to pivot */
x -= px;
y -= py;
*u = (x * c - y * s) + px;
*v = (x * s + y * c) + py;
}
void draw_sprite_rotate(gfx_context_t * ctx, sprite_t * sprite, int32_t x, int32_t y, float rotation, float alpha) {
double originx = (double)sprite->width / 2.0;
double originy = (double)sprite->height / 2.0;
/* Calculate corners */
double ul_x, ul_y;
double ll_x, ll_y;
double ur_x, ur_y;
double lr_x, lr_y;
calc_rotation(-sprite->width/2, -sprite->height/2, 0, 0, rotation, &ul_x, &ul_y);
calc_rotation(-sprite->width/2, sprite->height/2, 0, 0, rotation, &ll_x, &ll_y);
calc_rotation(sprite->width/2, -sprite->height/2, 0, 0, rotation, &ur_x, &ur_y);
calc_rotation(sprite->width/2, sprite->height/2, 0, 0, rotation, &lr_x, &lr_y);
/* Calculate bounds */
int32_t _left = min(min(ul_x, ll_x), min(ur_x, lr_x));
int32_t _top = min(min(ul_y, ll_y), min(ur_y, lr_y));
int32_t _right = max(max(ul_x, ll_x), max(ur_x, lr_x));
int32_t _bottom = max(max(ul_y, ll_y), max(ur_y, lr_y));
for (int32_t _y = _top; _y < _bottom; ++_y) {
if (_y + y < 0) continue;
if (_y + y >= ctx->height) break;
if (!_is_in_clip(ctx, y + _y)) continue;
for (int32_t _x = _left; _x < _right; ++_x) {
if (_x + x < 0) continue;
if (_x + x >= ctx->width) break;
double u, v;
calc_rotation(_x + originx, _y + originy, originx, originy, -rotation, &u, &v);
uint32_t n_color = getBilinearFilteredPixelColor(sprite, u / (double)sprite->width, v/(double)sprite->height);
uint32_t f_color = rgb(_ALP(n_color) * alpha, 0, 0);
GFX(ctx, x + _x, y + _y) = alpha_blend(GFX(ctx, x + _x, y + _y), n_color, f_color);
}
}
}