c++ - 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)。是否有绘制填充四边形或三角形的技巧？
目前我只是通过绘制大量线条(SDL_Drawlines)来填充它们，但性能很差。
我不想进入 OpenGL。

Answer 1

SDL_RenderGeometry() / SDL_RenderGeometryRaw() 最近(2021 年 8 月)添加到 SDL main :

/**
 * 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 仅缺少 Z 坐标的数据 channel affine texturing是可以实现的。