I want to learn OpenGL 3.0 with golang. But when i try to compile some code, i get many errors.
package main
import (
"os"
//"errors"
"fmt"
//gl "github.com/chsc/gogl/gl33"
//"github.com/jteeuwen/glfw"
"github.com/go-gl/gl"
"github.com/go-gl/glfw"
"runtime"
"time"
)
var (
width int = 640
height int = 480
)
var (
points = []float32{0.0, 0.8, -0.8, -0.8, 0.8, -0.8}
)
func initScene() {
gl.Init()
gl.ClearColor(0.0, 0.5, 1.0, 1.0)
gl.Enable(gl.CULL_FACE)
gl.Viewport(0, 0, 800, 600)
}
func glfwInitWindowContext() {
if err := glfw.Init(); err != nil {
fmt.Fprintf(os.Stderr, "glfw_Init: %s\n", err)
glfw.Terminate()
}
glfw.OpenWindowHint(glfw.FsaaSamples, 1)
glfw.OpenWindowHint(glfw.WindowNoResize, 1)
if err := glfw.OpenWindow(width, height, 0, 0, 0, 0, 32, 0, glfw.Windowed); err != nil {
fmt.Fprintf(os.Stderr, "glfw_Window: %s\n", err)
glfw.CloseWindow()
}
glfw.SetSwapInterval(1)
glfw.SetWindowTitle("Title")
}
func drawScene() {
for glfw.WindowParam(glfw.Opened) == 1 {
gl.Clear(gl.COLOR_BUFFER_BIT)
vertexShaderSrc := `#version 120
attribute vec2 coord2d;
void main(void) {
gl_Position = vec4(coord2d, 0.0, 1.0);
}`
vertexShader := gl.CreateShader(gl.VERTEX_SHADER)
vertexShader.Source(vertexShaderSrc)
vertexShader.Compile()
fragmentShaderSrc := `#version 120
void main(void) {
gl_FragColor[0] = 0.0;
gl_FragColor[1] = 0.0;
gl_FragColor[2] = 1.0;
}`
fragmentShader := gl.CreateShader(gl.FRAGMENT_SHADER)
fragmentShader.Source(fragmentShaderSrc)
fragmentShader.Compile()
program := gl.CreateProgram()
program.AttachShader(vertexShader)
program.AttachShader(fragmentShader)
program.Link()
attribute_coord2d := program.GetAttribLocation("coord2d")
program.Use()
//attribute_coord2d.AttribPointer(size, typ, normalized, stride, pointer)
attribute_coord2d.EnableArray()
attribute_coord2d.AttribPointer(0, 3, false, 0, &(points[0]))
//gl.DrawArrays(gl.TRIANGLES, 0, len(points))
gl.DrawArrays(gl.TRIANGLES, 0, 3)
glfw.SwapBuffers()
inputHandler()
time.Sleep(100 * time.Millisecond)
}
}
func inputHandler() {
glfw.Enable(glfw.StickyKeys)
if glfw.Key(glfw.KeyEsc) == glfw.KeyPress {
//gl.DeleteBuffers(2, &uiVBO[0])
glfw.Terminate()
}
if glfw.Key(glfw.KeyF2) == glfw.KeyPress {
glfw.SetWindowTitle("Title2")
fmt.Println("Changed to 'Title2'")
fmt.Println(len(points))
}
if glfw.Key(glfw.KeyF1) == glfw.KeyPress {
glfw.SetWindowTitle("Title1")
fmt.Println("Changed to 'Title1'")
}
}
func main() {
runtime.LockOSThread()
glfwInitWindowContext()
initScene()
drawScene()
}
And after that:
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x41bc6f74]
goroutine 1 [syscall]:
github.com/go-gl/gl._Cfunc_glDrawArrays(0x4, 0x7f8500000003)
/tmp/go-build463568685/github.com/go-gl/gl/_obj/_cgo_defun.c:610 +0x2f
github.com/go-gl/gl.DrawArrays(0x4, 0x3, 0x0, 0x45bd70)
/tmp/go-build463568685/github.com/go-gl/gl/_obj/gl.cgo1.go:1922 +0x33
main.drawScene()
/home/klink/Dev/Go/gogl/gopher/exper.go:85 +0x1e6
main.main()
/home/klink/Dev/Go/gogl/gopher/exper.go:116 +0x27
goroutine 2 [syscall]:
created by runtime.main
/build/buildd/golang-1/src/pkg/runtime/proc.c:221
exit status 2
