Fastest way to draw filled quad/triangle with the SDL2 renderer?-CodePudding

I have a game written using SDL2, and the SDL2 renderer (hardware accelerated) for drawing. Is there a trick to draw filled quads or triangles?

At the moment I'm filling them by just drawing lots of lines (SDL_Drawlines), but the performance stinks.

I don't want to go into OpenGL.

CodePudding user response：

SDL_RenderGeometry()/SDL_RenderGeometryRaw() were recently (August 2021) added to 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);

CodePudding user response：

Not possible. SDL2 does not include a full-fledged rendering engine.

Some options:

You could adopt Skia (the graphics library used in Chrome, among ohters) and then either stick with a software renderer, or instantiate an OpenGL context and use the hardware backend.
You could use another 2D drawing library such as Raylib
Or just bite the bullet and draw your triangles using OpenGL.