69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
#include <algorithm>
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#include <cmath>
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#include <vector>
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#include <SDL2/SDL_render.h>
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#include <basic_widgets/core/draw.hpp>
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#include <basic_widgets/core/math.hpp>
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#include <basic_widgets/core/texture.hpp>
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namespace bwidgets::core
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{
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auto aa(const SDL_Color& base_color, const int aa_pixels, const float d) noexcept
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-> SDL_Color
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{
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SDL_Color c {base_color};
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if (aa_pixels == 0) {
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if (d > 0) c.a = 0;
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}
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else {
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const auto factor = 1.0 - smoothstep<float>(d, (float)-aa_pixels, 0.);
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c.a = (uint8_t)((float)c.a * factor);
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}
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return c;
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}
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auto filled_circle(const SDL_Color& c, const int resolution, core::Renderer* r,
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const int aa_pixels) -> core::Texture*
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{
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auto* texture {new core::Texture(
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r, SDL_PIXELFORMAT_RGBA32, SDL_TEXTUREACCESS_STATIC, resolution, resolution)};
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const auto radius {resolution / 2};
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const SDL_Point center {radius, radius};
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set_pixels_color(
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texture,
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[aa_pixels, c, center, radius](const SDL_Point& p,
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const SDL_PixelFormat* format) -> uint32_t {
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const auto d_delta = core::distance(center, p) - (float)radius;
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const auto aa_color = aa(c, aa_pixels, d_delta);
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return SDL_MapRGBA(format, aa_color.r, aa_color.g, aa_color.b, aa_color.a);
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});
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texture->blend_mode(SDL_BLENDMODE_BLEND);
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texture->scale_mode(SDL_ScaleModeNearest);
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return texture;
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}
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void set_pixels_color(
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core::Texture* t,
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const std::function<Uint32(const SDL_Point&, const SDL_PixelFormat*)>& pixel_color)
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{
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auto attr = t->attributes();
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auto pitch = attr.w * attr.format->BytesPerPixel;
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std::vector<uint32_t> pixels;
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pixels.reserve(attr.h * (std::vector<uint32_t>::size_type)pitch);
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for (auto y = 0; y < attr.h; y++) {
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for (auto x = 0; x < attr.w; x++) {
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pixels.push_back(pixel_color({x, y}, attr.format));
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}
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}
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t->update(nullptr, (const void*)pixels.data(), pitch);
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}
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}
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