diff options
Diffstat (limited to 'sponge.h')
| -rw-r--r-- | sponge.h | 34 |
1 files changed, 23 insertions, 11 deletions
@@ -179,7 +179,6 @@ void sponge_draw_line(sponge_Texture c, int32_t x0, int32_t y0, int32_t x1, int3 dx = SPONGE__ABS(dx); int32_t dy = y1 - y0; dy = SPONGE__ABS(dy); - int32_t d = (2 * dy) - dx; int32_t sx = (x0 < x1) ? 1 : -1; int32_t sy = (y0 < y1) ? 1 : -1; @@ -222,13 +221,7 @@ void sponge_draw_triangle_col(sponge_Texture c, int32_t x0, int32_t y0, int32_t sponge_draw_triangle_col3(c, x0, y0, x1, y1, x2, y2, color, color, color); } -// NOTE(kard): -// this does not accept floats on purpose. -// there are more efficient algorithms for producing triangle pixels other than -// checking every one of them in rectangle with barycentric coords (e.g. using Brehensam algorithm) -// and they can work with integer coordinates. -// TODO(kard): this should be explored in the future -// TODO(kard): backface culling? +// NOTE(kard): requires vertices to be in clockwise order void sponge_draw_triangle_col3( sponge_Texture c, int32_t x0, int32_t y0, int32_t x1, int32_t y1, int32_t x2, int32_t y2, uint32_t color0, uint32_t color1, uint32_t color2) { @@ -256,14 +249,34 @@ void sponge_draw_triangle_col3( sponge__ColorF color1f = sponge__colf_unpack(color1); sponge__ColorF color2f = sponge__colf_unpack(color2); + int32_t edge0 = ((y0 - y1) * min_x) + ((x1 - x0) * min_y) + ((x0 * y1) - (x1 * y0)); + int32_t edge1 = ((y1 - y2) * min_x) + ((x2 - x1) * min_y) + ((x1 * y2) - (x2 * y1)); + int32_t edge2 = ((y2 - y0) * min_x) + ((x0 - x2) * min_y) + ((x2 * y0) - (x0 * y2)); + for (uint32_t y = min_y; y <= max_y; y++, row += c.stride) { - for (uint32_t x = x0; x <= max_x; x++) { + int32_t edge0a = edge0; + int32_t edge1a = edge1; + int32_t edge2a = edge2; + edge0 += (x1 - x0); + edge1 += (x2 - x1); + edge2 += (x0 - x2); + + for (uint32_t x = min_x; x <= max_x; x++) { + int32_t edge0b = edge0a; + int32_t edge1b = edge1a; + int32_t edge2b = edge2a; + edge0a += (y0 - y1); + edge1a += (y1 - y2); + edge2a += (y2 - y0); + if (edge0b < 0 || edge1b < 0 || edge2b < 0) { + continue; + } + float u, v, w; sponge_Vec2 p = { .x = (float)x, .y = (float)y }; sponge__barycentric(ctx, p, t0, t1, t2, &u, &v, &w); if (u > 0.0f && v > 0.0f && w > 0.0f) { - // TODO(kard): make more robust, this probably has a lot of off by 1 errors sponge__ColorF c0 = sponge__colf_mul(color0f, u); sponge__ColorF c1 = sponge__colf_mul(color1f, v); sponge__ColorF c2 = sponge__colf_mul(color2f, w); @@ -275,4 +288,3 @@ void sponge_draw_triangle_col3( } #endif // SPONGE_IMPLEMENTATION - |