add hellotriangle for opengl 4.6

gl46core-hellotriangle/main.go

@@ -0,0 +1,177 @@
+// Copyright 2021 The go-gl Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Renders a red triangle using GLFW 3.3 and OpenGL 4.6 core forward-compatible profile.
+package main
+
+import (
+ "errors"
+ "fmt"
+ _ "image/png"
+ "log"
+ "runtime"
+
+ "github.com/go-gl/gl/v4.6-core/gl"
+ "github.com/go-gl/glfw/v3.3/glfw"
+)
+
+const windowWidth = 800
+const windowHeight = 600
+
+func init() {
+ // GLFW event handling must run on the main OS thread
+ runtime.LockOSThread()
+}
+
+func main() {
+ if err := glfw.Init(); err != nil {
+ log.Fatalln("failed to initialize glfw:", err)
+ }
+ defer glfw.Terminate()
+
+ glfw.WindowHint(glfw.Resizable, glfw.False)
+ glfw.WindowHint(glfw.ContextVersionMajor, 4)
+ glfw.WindowHint(glfw.ContextVersionMinor, 1)
+ glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
+ glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)
+ window, err := glfw.CreateWindow(windowWidth, windowHeight, "Hello colorful triangle", nil, nil)
+ if err != nil {
+ panic(err)
+ }
+ window.MakeContextCurrent()
+
+ // Initialize Glow.
+ if err := gl.Init(); err != nil {
+ panic(err)
+ }
+
+ version := gl.GoStr(gl.GetString(gl.VERSION))
+ fmt.Println("OpenGL version", version)
+
+ // Compile, link and validate vertex and fragment shaders.
+ program, err := CompileProgram(vertexShader, fragmentShader)
+ if err != nil {
+ panic(err)
+ }
+ gl.UseProgram(program)
+ gl.BindFragDataLocation(program, 0, gl.Str("outputColor\x00"))
+
+ // Configure the vertex data
+ var vao uint32
+ gl.GenVertexArrays(1, &vao)
+ gl.BindVertexArray(vao)
+
+ // float32 is 4 bytes wide.
+ const attrSize = 4
+ var vbo uint32
+ gl.GenBuffers(1, &vbo)
+ gl.BindBuffer(gl.ARRAY_BUFFER, vbo)
+ gl.BufferData(gl.ARRAY_BUFFER, attrSize*len(triangleVertices), gl.Ptr(triangleVertices), gl.STATIC_DRAW)
+ vertAttrib := uint32(gl.GetAttribLocation(program, gl.Str("vert\x00")))
+ gl.EnableVertexAttribArray(vertAttrib)
+
+ // Stride is 2 since our data is 2D.
+ gl.VertexAttribPointerWithOffset(vertAttrib, 3, gl.FLOAT, false, 2*attrSize, 0)
+
+ for !window.ShouldClose() {
+ gl.Clear(gl.COLOR_BUFFER_BIT)
+ gl.BindVertexArray(vao)
+ gl.DrawArrays(gl.TRIANGLES, 0, 3)
+ // Maintenance
+ window.SwapBuffers()
+ glfw.PollEvents()
+ if window.GetKey(glfw.KeyEscape) == glfw.Press {
+ window.SetShouldClose(true)
+ }
+ }
+}
+
+var vertexShader string = `
+#version 330
+in vec3 vert;
+
+void main() {
+ gl_Position = vec4(vert,1);
+}
+` + "\x00"
+
+var fragmentShader string = `
+#version 330
+out vec4 outputColor;
+
+void main() {
+ outputColor = vec4(1.0,0.0,0.0,1.0);
+}
+` + "\x00"
+
+var triangleVertices = []float32{
+ -1.0, -1.0,
+ 1.0, -1.0,
+ 0.0, 1.0,
+}
+
+func CompileProgram(vertexSrcCode, fragmentSrcCode string) (program uint32, err error) {
+ program = gl.CreateProgram()
+ vid, err := compile(gl.VERTEX_SHADER, vertexSrcCode)
+ if err != nil {
+ return 0, fmt.Errorf("vertex shader compile: %w", err)
+ }
+ fid, err := compile(gl.FRAGMENT_SHADER, fragmentSrcCode)
+ if err != nil {
+ return 0, fmt.Errorf("fragment shader compile: %w", err)
+ }
+ gl.AttachShader(program, vid)
+ gl.AttachShader(program, fid)
+ gl.LinkProgram(program)
+ log := ivLog(program, gl.LINK_STATUS, gl.GetProgramiv, gl.GetProgramInfoLog)
+ if len(log) > 0 {
+ return 0, fmt.Errorf("link failed: %v", log)
+ }
+ // We should technically call DetachShader after linking... https://www.youtube.com/watch?v=71BLZwRGUJE&list=PLlrATfBNZ98foTJPJ_Ev03o2oq3-GGOS2&index=7&ab_channel=TheCherno
+ gl.ValidateProgram(program)
+ log = ivLog(program, gl.VALIDATE_STATUS, gl.GetProgramiv, gl.GetProgramInfoLog)
+ if len(log) > 0 {
+ return 0, fmt.Errorf("validation failed: %v", log)
+ }
+
+ // We can clean up.
+ gl.DeleteShader(vid)
+ gl.DeleteShader(fid)
+ return program, nil
+}
+
+func compile(shaderType uint32, sourceCode string) (uint32, error) {
+ id := gl.CreateShader(shaderType)
+ csources, free := gl.Strs(sourceCode)
+ gl.ShaderSource(id, 1, csources, nil)
+ free()
+ gl.CompileShader(id)
+
+ // We now check the errors during compile, if there were any.
+ log := ivLog(id, gl.COMPILE_STATUS, gl.GetShaderiv, gl.GetShaderInfoLog)
+ if len(log) > 0 {
+ return 0, errors.New(log)
+ }
+ return id, nil
+}
+
+// ivLog is a helper function for extracting log data
+// from a Shader compilation step or program linking.
+//
+// log := ivLog(id, gl.COMPILE_STATUS, gl.GetShaderiv, gl.GetShaderInfoLog)
+// if len(log) > 0 {
+// return 0, errors.New(log)
+// }
+func ivLog(id, plName uint32, getIV func(program uint32, pname uint32, params *int32), getInfo func(program uint32, bufSize int32, length *int32, infoLog *uint8)) string {
+ var iv int32
+ getIV(id, plName, &iv)
+ if iv == gl.FALSE {
+ var logLength int32
+ getIV(id, gl.INFO_LOG_LENGTH, &logLength)
+ log := make([]byte, logLength)
+ getInfo(id, logLength, &logLength, &log[0])
+ return string(log[:len(log)-1]) // we exclude the last null character.
+ }
+ return ""
+}