go + SDL + OpenGL + MacOS 示例 = 我在 DrawArrays() 之后得到INVALID_O

Question

SDL 版本：2.0.12
OpenGL 版本：3.3 英特尔-10.4.14
我不得不通过请求核心配置文件来强制 OpenGL 版本为 3.3，否则我会得到的默认版本是 1.2

按照这个视频教程 http://youtu.be/yxAPS2eyKmA围棋游戏，我尝试了OpenGL示例代码，它只显示了一个黑色窗口。
它应该呈现一个橙色三角形。

我在倒数第二句话之后INVALID_OPERATIONgl.DrawArrays(gl.TRIANGLES, 0, 3)

https://gist.github.com/ErnestoBorio/87b09bf3cc496657a83637fd4876e943

package main
import (
"fmt"
"strings"
"github.com/go-gl/gl/v3.3-core/gl"
"github.com/veandco/go-sdl2/sdl"
)
func DontPanic(err error) {
if err != nil {
panic(err)
}
}
var GLversion = [...]int {3, 3}
func main() {
DontPanic(
sdl.Init(sdl.INIT_EVERYTHING))
defer sdl.Quit()
DontPanic(
sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE))
DontPanic(
sdl.GLSetAttribute(sdl.GL_CONTEXT_MAJOR_VERSION, GLversion[0]))
DontPanic(
sdl.GLSetAttribute(sdl.GL_CONTEXT_MINOR_VERSION, GLversion[1]))
window, err := sdl.CreateWindow("OpenGL", 200, 200, 1280, 720, sdl.WINDOW_OPENGL)
DontPanic(err)
window.GLCreateContext()
defer window.Destroy()
GLversionStr := fmt.Sprintf("%d%d0", GLversion[0], GLversion[1])
gl.Init()
version := gl.GoStr(gl.GetString(gl.VERSION))
fmt.Println("OpenGL Version", version)
vertexShaderSrc :=
"#version "+ GLversionStr +" core n"+
"layout (location = 0) in vec3 aPos;"+
"void main() {"+
"gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);"+
"}x00"
vertexShader := gl.CreateShader(gl.VERTEX_SHADER)
csource, free := gl.Strs(vertexShaderSrc)
gl.ShaderSource(vertexShader, 1, csource, nil)
free()
gl.CompileShader(vertexShader)
var status int32
gl.GetShaderiv(vertexShader, gl.COMPILE_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetShaderiv(vertexShader, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("x00", int(logLength+1))
gl.GetShaderInfoLog(vertexShader, logLength, nil, gl.Str(log))
panic("Failed to compile vertex shader:n" + log)
}
fragmentShaderSrc :=
"#version "+ GLversionStr +" core n"+
"out vec4 FragColor;"+
"void main() {"+
"FragColor = vec4(1, 0.5, 0.2, 1);"+
"}x00"
fragmentShader := gl.CreateShader(gl.FRAGMENT_SHADER)
csource, free = gl.Strs(fragmentShaderSrc)
gl.ShaderSource(fragmentShader, 1, csource, nil)
free()
gl.CompileShader(fragmentShader)
gl.GetShaderiv(fragmentShader, gl.COMPILE_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetShaderiv(fragmentShader, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("x00", int(logLength+1))
gl.GetShaderInfoLog(fragmentShader, logLength, nil, gl.Str(log))
panic("Failed to compile fragment shader:n" + log)
}
shaderPrg := gl.CreateProgram()
gl.AttachShader(shaderPrg, vertexShader)
gl.AttachShader(shaderPrg, fragmentShader)
gl.LinkProgram(shaderPrg)
gl.GetProgramiv(shaderPrg, gl.LINK_STATUS, &status)
if status == gl.FALSE {
panic("Error in Linker, error logging not yet implemented.")
}
gl.DeleteShader(vertexShader)
gl.DeleteShader(fragmentShader)
vertices := []float32{
-.5, -.5, 0,
.5, -.5, 0,
0,  .5, 0,
}
var vertexBuffer uint32
gl.GenBuffers(1, &vertexBuffer)
gl.BindBuffer(gl.ARRAY_BUFFER, vertexBuffer)
var vertexArray uint32
gl.GenVertexArrays(1, &vertexArray)
gl.BindVertexArray(vertexArray)
gl.BufferData(gl.ARRAY_BUFFER, len(vertices)*4, gl.Ptr(vertices), gl.STATIC_DRAW)
gl.VertexAttribPointer(0, 3, gl.FLOAT, false, 3*4, nil)
gl.EnableVertexAttribArray(0)
gl.BindVertexArray(0)
EventPoll:
for {
for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
switch event.(type) {
case *sdl.QuitEvent:
break EventPoll
}
}
gl.ClearColor(0, 0, 0, 0)
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.BindVertexArray(vertexArray)
gl.DrawArrays(gl.TRIANGLES, 0, 3)
window.GLSwap()
}
}

Answer 1

您的代码从不调用glUseProgram这意味着您尝试在没有当前程序对象的情况下进行绘制，这在核心配置文件 OpenGL 中无效。