Why Can\'t I Display a Triangle Using go-gl/glfw and github.com/banthar/gl Despite Successful Window and Background Setup?

Vertex Buffers and Displaying Triangles in Go

Question:

Using the Go github.com/banthar/gl package, the tutorial code from http://www.opengl-tutorial.org/beginners-tutorials/tutorial-2-the-first-triangle/ successfully creates a window and sets the background color, but fails to display a triangle. The equivalent C code does display the triangle. Why?

Answer:

The errors may be attributed to incorrect arguments passed to the AttribPointer function. The following adjustments have been identified to resolve the issue:

• AttribPointer Arguments: Pass nil for the array buffer offset instead of (void*)0. This tells the OpenGL library to use the current buffer binding as the starting point for the vertex attribute.
• BufferData Size: Specify the size of the vertex buffer in bytes instead of the number of elements. For example, if the vertex buffer contains n 32-bit floating-point values, pass 4 * n to BufferData.

Corrected Go Code:

package main

import (
    "github.com/banthar/gl"
    "github.com/go-gl/glfw/v3.2/glfw"
    "log"
)

func main() {
    // ... ( GLFW window setup, GL initialization code) ...

    // Create vertex buffer
    gVertexBufferData := []float32{-1.0, -1.0, 0.0, 1.0, -1.0, 0.0, 0.0, 1.0, 0.0}
    vertexBuffer := gl.GenBuffer()
    vertexBuffer.Bind(gl.ARRAY_BUFFER)
    gl.BufferData(gl.ARRAY_BUFFER, len(gVertexBufferData)*4, gVertexBufferData, gl.STATIC_DRAW)

    for {
        // ... (Clear screen, enable/disable vertex attrib, draw triangle) ...
        vertexAttrib.AttribPointer(
            3,     // Size
            gl.FLOAT, // Type
            false, // Normalized?
            0,     // Stride
            nil)   // Array buffer offset

        // ... (Continue drawing loop) ...
    }
}

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