使用 SDL2 渲染器绘制填充四边形/三角形的最快方法？

Question

我有一个使用 SDL2 编写的游戏，以及用于绘图的 SDL2 渲染器（硬件加速）。绘制填充的四边形或三角形有技巧吗？

目前我只是通过绘制大量线条 (SDL_Drawlines) 来填充它们，但是性能很糟糕。

我不想进入 OpenGL。

Answer 1

SDL_RenderGeometry()/SDL_RenderGeometryRaw() 被添加到SDL 2.0.18:

/**
 * The structure that defines a point (floating point)
 *
 * \sa SDL_EnclosePoints
 * \sa SDL_PointInRect
 */
typedef struct SDL_FPoint
{
    float x;
    float y;
} SDL_FPoint;

...

/**
 *  Vertex structure
 */
typedef struct SDL_Vertex
{
    SDL_FPoint position;        /**< Vertex position, in SDL_Renderer coordinates  */
    SDL_Color  color;           /**< Vertex color */
    SDL_FPoint tex_coord;       /**< Normalized texture coordinates, if needed */
} SDL_Vertex;

...

/**
 * Render a list of triangles, optionally using a texture and indices into the
 * vertex array Color and alpha modulation is done per vertex
 * (SDL_SetTextureColorMod and SDL_SetTextureAlphaMod are ignored).
 *
 * \param texture (optional) The SDL texture to use.
 * \param vertices Vertices.
 * \param num_vertices Number of vertices.
 * \param indices (optional) An array of integer indices into the 'vertices'
 *                array, if NULL all vertices will be rendered in sequential
 *                order.
 * \param num_indices Number of indices.
 * \return 0 on success, or -1 if the operation is not supported
 *
 * \sa SDL_Vertex
 */
extern DECLSPEC int SDLCALL SDL_RenderGeometry(SDL_Renderer *renderer,
                                               SDL_Texture *texture,
                                               const SDL_Vertex *vertices, int num_vertices,
                                               const int *indices, int num_indices);

/**
 * Render a list of triangles, optionally using a texture and indices into the
 * vertex arrays Color and alpha modulation is done per vertex
 * (SDL_SetTextureColorMod and SDL_SetTextureAlphaMod are ignored).
 *
 * \param texture (optional) The SDL texture to use.
 * \param xy Vertex positions
 * \param xy_stride Byte size to move from one element to the next element
 * \param color Vertex colors (as SDL_Color)
 * \param color_stride Byte size to move from one element to the next element
 * \param uv Vertex normalized texture coordinates
 * \param uv_stride Byte size to move from one element to the next element
 * \param num_vertices Number of vertices.
 * \param indices (optional) An array of indices into the 'vertices' arrays,
 *                if NULL all vertices will be rendered in sequential order.
 * \param num_indices Number of indices.
 * \param size_indices Index size: 1 (byte), 2 (short), 4 (int)
 * \return 0 on success, or -1 if the operation is not supported
 */
extern DECLSPEC int SDLCALL SDL_RenderGeometryRaw(SDL_Renderer *renderer,
                                               SDL_Texture *texture,
                                               const float *xy, int xy_stride,
                                               const int *color, int color_stride,
                                               const float *uv, int uv_stride,
                                               int num_vertices,
                                               const void *indices, int num_indices, int size_indices);

请注意，由于 API 缺少 Z 坐标的数据通道，因此只能实现 affine texturing。

Answer 2

不可能。 SDL2 不包含成熟的渲染引擎。

一些选项：

• 您可以采用Skia（Chrome 中使用的图形库，等等），然后要么坚持使用软件渲染器，要么实例化 OpenGL 上下文并使用硬件后端。

• 您可以使用另一个 2D 绘图库，例如 Raylib

• 或者只是硬着头皮使用 OpenGL 绘制三角形。