ImageDrawLine() is one pixel short?

[Kaggen67]

Hi!
I'm pretty new to raylib. I'm using version 5.5 on Windows 11 with an NVIDIA GeForce RTX 5070 Ti graphics card. I use w64devkit for development.

Strange thing is when I use ImageDrawLine() function it seems it draw one pixel less than it should.
ImageDrawLine(&img, 0,10, 10, 10, WHITE) f.ex. should draw 11 pixels in X-direction, but draws only 10 (0-9).

I've seen some bug report about the DrawLine() function regarding misplaced pixels, but that seems to depend on the GPU hardware. As I understand it ImageDrawLine() use software line drawing (CPU)?

Is this a bug or am I missing something? The code below describes the problem. I draw two vertical lines (up-down, down up) and two horizontal (right-left, left right) all misses a pixel at the end, regardless which way they are drawn.

#include "raylib.h"

#define WINDOW_WIDTH 640
#define WINDOW_HEIGHT 640
#define IMG_WIDTH 128
#define IMG_HEIGHT 128
#define SCALE 4

Image img;
Texture2D tex;

int main() {

	float x_center = (WINDOW_WIDTH - (IMG_WIDTH * SCALE)) / 2;
	float y_center = (WINDOW_HEIGHT - (IMG_HEIGHT * SCALE)) / 2;
	InitWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "ImageDrawLine()");
	img = GenImageColor(IMG_WIDTH, IMG_HEIGHT, BLACK);
	ImageDrawLine(&img, 64, 0, 64, 127, WHITE); // Draw up-down
	ImageDrawLine(&img, 66, 127, 66, 0, WHITE); // Draw down-up
	ImageDrawLine(&img, 0,64, 127, 64, WHITE);  // Draw left-right
	ImageDrawLine(&img, 127, 66, 0, 66, WHITE); // Draw right-left
	tex = LoadTextureFromImage(img);
	SetTargetFPS(60);

	// Main loop
	while(!WindowShouldClose()) {
		BeginDrawing();
		ClearBackground(GRAY);
		DrawTextureEx(tex, Vector2 {x_center, y_center}, 0.0f, SCALE, WHITE);
		EndDrawing();
	}

	UnloadTexture(tex);
	UnloadImage(img);
	return 0;
}

[raysan5]

@Kaggen67 First, you should try with latest raylib from GitHub master branch, it's 2000 commits ahead from 5.5.

In any case, it could be one pixel off for ImageDrawLine() depending on the maths rounding, try with straight lines also.

[Kaggen67]

Downloaded and compiled master branch and the problem remains. I attach a screenshot of what i get when running the code I posted previously.

To clarify, the lines in the screenshot should go all the way to the edge of the black sqaure. I also tested drawing shorter lines. A horizontal line from x1 = 1 to x2 = 2 should set two pixels, it only draws one, so it seems it consistently draws one pixel less than it should at least regarding horizontal and vertical straight lines.