al_draw_soft_line(3)

💅 al_draw_soft_line

okay so real talk, bestie — this is from the Allegro 5 API, and it's the lowkey MVP of the primitives addon: it's the one that lets you do the pixel pushing. 🎀

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✨ NAME ✨

al_draw_soft_line — the Allegro 5 API function that draws a line with the software rasterizer and hands the per-pixel work off to functions you supply 🫶

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🌸 SYNOPSIS 🌸

#include <allegro5/allegro_primitives.h>

void al_draw_soft_line(ALLEGRO_VERTEX* v1, ALLEGRO_VERTEX* v2, uintptr_t state,
   void (*first)(uintptr_t, int, int, ALLEGRO_VERTEX*, ALLEGRO_VERTEX*),
   void (*step)(uintptr_t, int),
   void (*draw)(uintptr_t, int, int))

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💖 DESCRIPTION 💖

So what it does is draw a line using the software rasterizer plus user supplied pixel functions. It's giving "build your own shading routine" energy, fr fr. 🌈

If you want help understanding what these functions actually do, go peek at the implementation of the various shading routines in addons/primitives/line_soft.c — that's the blueprint, iykyk. 👑

And the line is drawn top to bottom. Noted. 💅

🦋 Parameters 🦋

• v1, v2 — the two vertices of the line 💜
• state — a pointer to a user supplied struct; this struct gets passed to all the pixel functions. It's literally the main character carrying the context around 👑
• first — called before drawing the first pixel of the line. It gets passed the coordinates of this pixel, plus the two vertices above. Careful though: the passed vertices may have been altered by clipping 🙈
• step — called once per pixel. The second parameter is set to 1 if the step is a minor step, and 0 if this step is a major step. Minor steps are taken only either in x or y directions. Major steps are taken in both directions diagonally. In all cases, the absolute value of the change in coordinate is at most 1 in either direction ⭐
• draw — called once per pixel. The function is expected to draw the pixel at the coordinates passed to it 🔥

ngl bestie, the step rules are the whole vibe check of this function — minor = one axis, major = diagonal, and never more than 1 of movement per axis. Write that down. 📝

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🎀 SEE ALSO 🎀

• al_draw_line(3)

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and that's the whole page, bestie — no cap, every flag and every note intact 💖✨

signing off from the Allegro reference manual 💫 (source of all this wisdom, mwah) 🧚💜