Ep4: Buffers package

buffers/buffers.go

@@ -2,34 +2,111 @@ package buffers
 
 import (
 	"github.com/bloeys/go-sdl-engine/logging"
-	"github.com/bloeys/go-sdl-engine/shaders"
 	"github.com/go-gl/gl/v4.6-compatibility/gl"
 )
 
-func HandleBuffers(sp shaders.ShaderProgram) {
+type BufferType int
 
-	//Create and fill Vertex buffer object
+const (
+	BufTypeUnknown BufferType = iota
+	BufTypeVertPos
+	BufTypeColor
+)
+
+type BufferGLType int
+
+const (
+	//Generic array of data. Should be used for most data like vertex positions, vertex colors etc.
+	BufGLTypeArrayBuffer BufferGLType = gl.ARRAY_BUFFER
+)
+
+type BufferUsage int
+
+const (
+	//Buffer is set only once and used many times
+	BufUsageStatic BufferUsage = gl.STATIC_DRAW
+	//Buffer is changed a lot and used many times
+	BufUsageDynamic BufferUsage = gl.DYNAMIC_DRAW
+	//Buffer is set only once and used by the GPU at most a few times
+	BufUsageStream BufferUsage = gl.STREAM_DRAW
+)
+
+type Buffer struct {
+	ID     uint32
+	Type   BufferType
+	GLType BufferGLType
+	DataTypeInfo
+}
+
+func (b *Buffer) Activate() {
+	gl.BindBuffer(uint32(b.GLType), b.ID)
+}
+
+func (b *Buffer) Deactivate() {
+	gl.BindBuffer(uint32(b.GLType), 0)
+}
+
+type BufferObject struct {
+	VAOID      uint32
+	VertPosBuf *Buffer
+	ColorBuf   *Buffer
+}
+
+func (bo *BufferObject) GenBuffer(data []float32, bufUsage BufferUsage, bufType BufferType, bufDataType DataType) {
+
+	gl.BindVertexArray(bo.VAOID)
+
+	//Create vertex buffer object
 	var vboID uint32
 	gl.CreateBuffers(1, &vboID)
 	if vboID == 0 {
 		logging.ErrLog.Println("Failed to create openGL buffer")
 	}
 
-	gl.BindBuffer(gl.ARRAY_BUFFER, vboID)
-
-	vertices := []float32{
-		-0.5, 0.5, 0,
-		0.5, 0.5, 0,
-		-0.5, -0.5, 0,
-
-		0.5, 0.5, 0,
-		0.5, -0.5, 0,
-		-0.5, -0.5, 0,
+	buf := &Buffer{
+		ID:           vboID,
+		Type:         bufType,
+		GLType:       BufGLTypeArrayBuffer,
+		DataTypeInfo: GetDataTypeInfo(bufDataType),
 	}
-	gl.BufferData(gl.ARRAY_BUFFER, 4*len(vertices), gl.Ptr(vertices), gl.STATIC_DRAW)
+	bo.SetBuffer(buf)
 
-	//Assign the VBO to vertPos attribute
-	vertPosLoc := sp.GetAttribLoc("vertPos")
-	gl.VertexAttribPointer(uint32(vertPosLoc), 3, gl.FLOAT, false, 3*4, gl.PtrOffset(0))
-	gl.EnableVertexAttribArray(uint32(vertPosLoc))
+	//Fill buffer with data
+	gl.BindBuffer(uint32(buf.GLType), buf.ID)
+	gl.BufferData(uint32(buf.GLType), int(buf.DataTypeInfo.ElementSize)*len(data), gl.Ptr(data), uint32(bufUsage))
+
+	//Unbind everything
+	gl.BindVertexArray(0)
+	gl.BindBuffer(uint32(buf.GLType), 0)
+}
+
+func (bo *BufferObject) SetBuffer(buf *Buffer) {
+
+	switch buf.Type {
+	case BufTypeVertPos:
+		bo.VertPosBuf = buf
+	case BufTypeColor:
+		bo.ColorBuf = buf
+	default:
+		logging.WarnLog.Println("Unknown buffer type in SetBuffer. Type:", buf.Type)
+	}
+}
+
+func (bo *BufferObject) Activate() {
+	gl.BindVertexArray(bo.VAOID)
+}
+
+func (bo *BufferObject) Deactivate() {
+	gl.BindVertexArray(0)
+}
+
+func NewBufferObject() *BufferObject {
+
+	var vaoID uint32
+	gl.CreateVertexArrays(1, &vaoID)
+	if vaoID == 0 {
+		logging.ErrLog.Println("Failed to create openGL vertex array object")
+	}
+
+	return &BufferObject{VAOID: vaoID}
 }