Is it possible to draw triangles or polygons?

[rh12503]

Looking at the source code, there doesn't seem to be any way to draw triangles or polygons.

Is there any way to access lower-level functions to achieve this, or is this being planned for a future update?

Thanks!

[gonutz]

Until now I have had no plan to include polygons. I could, though. What is your use case?

[rh12503]

Thanks for your fast reply! I've been experimenting with a visual effect that uses triangles, and I've really enjoyed using this library so I thought I would start here. It's not too important though, and I'm sure I could find some workarounds on my own.

[rh12503]

I managed to add my own FillTriangle and DrawTriangle functions to a copy of this library, so my issue is solved. It still would be cool to have a polygon function, but I'm not sure if that would be in line with this project's vision.

[gonutz]

I think that actually a DrawPolygon and FillPolygon function would be nice to have. It would increase the API size by two functions which is OK for the benefit it brings in my opinion. I am currently spending my free time on the wui library (it gets a graphical GUI designer) but when I get around to it I will look into implementing this. The main problem will be that the SDL2 backend does not support drawing triangles if I remember correctly. For the DirectX and OpenGL backends it will be no problem.

Can you share your version of the code?

[rh12503]

I couldn't get SDL2 working on my system, but I'm pretty sure it should be able to draw triangles. Here's my code for GLFW:

func (w *window) DrawTriangle(x0, y0, x1, y1, x2, y2 int, color Color) {
	gl.Begin(gl.LINE_STRIP)
	gl.Color4f(color.R, color.G, color.B, color.A)
	gl.Vertex2f(float32(x0)+0.5, float32(y0)+0.5)
	gl.Vertex2f(float32(x1)-0.5, float32(y1)+0.5)
	gl.Vertex2f(float32(x2)-0.5, float32(y2)-0.5)
	gl.Vertex2f(float32(x0)+0.5, float32(y0)-0.5)
	gl.End()
}

func (w *window) FillTriangle(x0, y0, x1, y1, x2, y2 int, color Color) {
	gl.Begin(gl.TRIANGLES)
	gl.Color4f(color.R, color.G, color.B, color.A)
	gl.Vertex2i(int32(x0), int32(y0))
	gl.Vertex2i(int32(x1), int32(y1))
	gl.Vertex2i(int32(x2), int32(y2))
	gl.End()
}

[sadek69]

Hi very good and easy for use engine,how use different colour exclude this predefined colors?

[gonutz]

There are functions draw.RGB(r, g, b float32) and draw.RGBA(r, g, b, a float32) which take color channel values in the range 0.0 .. 1.0.

[sadek69]

thanks