VBOs+attributes+drawing with VBOs

buffers/buffers.go

@@ -0,0 +1,35 @@
+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) {
+
+	//Create and fill 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,
+	}
+	gl.BufferData(gl.ARRAY_BUFFER, 4*len(vertices), gl.Ptr(vertices), gl.STATIC_DRAW)
+
+	//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))
+}

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"github.com/bloeys/go-sdl-engine/buffers"
 	"github.com/bloeys/go-sdl-engine/input"
 	"github.com/bloeys/go-sdl-engine/logging"
 	"github.com/bloeys/go-sdl-engine/shaders"
@@ -15,8 +16,9 @@ const (
 
 var (
 	isRunning bool = true
+	window    *sdl.Window
 
-	window *sdl.Window
+	simpleShader shaders.ShaderProgram
 )
 
 func main() {
@@ -41,6 +43,8 @@ func main() {
 	initOpenGL()
 	loadShaders()
 
+	buffers.HandleBuffers(simpleShader)
+
 	//Game loop
 	for isRunning {
 
@@ -69,13 +73,13 @@ func initOpenGL() {
 	sdl.GLSetAttribute(sdl.GL_DOUBLEBUFFER, 1)
 	gl.ClearColor(0, 0, 0, 1)
 
-	sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_COMPATIBILITY)
+	sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE)
-	// sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE)
 }
 
 func loadShaders() {
 
-	simpleShader, err := shaders.NewShaderProgram()
+	var err error
+	simpleShader, err = shaders.NewShaderProgram()
 	if err != nil {
 		logging.ErrLog.Fatalln("Failed to create new shader program. Err: ", err)
 	}
@@ -121,17 +125,9 @@ func draw() {
 
 	gl.Clear(gl.COLOR_BUFFER_BIT)
 
-	gl.Begin(gl.TRIANGLES)
+	simpleShader.Use()
-
+	//DRAW
-	gl.Vertex3f(-0.5, 0.5, 0)
+	gl.DrawArrays(gl.TRIANGLES, 0, 6)
-	gl.Vertex3f(0.5, 0.5, 0)
-	gl.Vertex3f(-0.5, -0.5, 0)
-
-	gl.Vertex3f(0.5, 0.5, 0)
-	gl.Vertex3f(0.5, -0.5, 0)
-	gl.Vertex3f(-0.5, -0.5, 0)
-
-	gl.End()
 
 	window.GLSwap()
 }

res/shaders/simple.frag.glsl

@@ -1,8 +1,8 @@
 #version 460
 
-out vec4 FragColor;
+out vec4 fragColor;
 
 void main()
 {
-    FragColor = vec4(1, 0, 0, 1.0);
+    fragColor = vec4(1, 1, 1, 1.0);
 } 

res/shaders/simple.vert.glsl

@@ -4,5 +4,5 @@ in vec3 vertPos;
 
 void main()
 {
-    gl_Position = vec4(vertPos, 1.0);
+    gl_Position = vec4(vertPos, 1.0); // vec4(vertPos.x, vertPos.y, vertPos.z, 1.0)
 }

shaders/shader_program.go

@@ -0,0 +1,49 @@
+package shaders
+
+import (
+	"github.com/bloeys/go-sdl-engine/logging"
+	"github.com/go-gl/gl/v4.6-compatibility/gl"
+)
+
+type ShaderProgram struct {
+	ID           uint32
+	VertShaderID uint32
+	FragShaderID uint32
+}
+
+func (sp *ShaderProgram) AttachShader(shader Shader) {
+
+	gl.AttachShader(sp.ID, shader.ID)
+	switch shader.ShaderType {
+	case VertexShaderType:
+		sp.VertShaderID = shader.ID
+	case FragmentShaderType:
+		sp.FragShaderID = shader.ID
+	default:
+		logging.ErrLog.Println("Unknown shader type ", shader.ShaderType, " for ID ", shader.ID)
+	}
+}
+
+func (sp *ShaderProgram) Link() {
+
+	gl.LinkProgram(sp.ID)
+
+	if sp.VertShaderID != 0 {
+		gl.DeleteShader(sp.VertShaderID)
+	}
+	if sp.FragShaderID != 0 {
+		gl.DeleteShader(sp.FragShaderID)
+	}
+}
+
+func (sp *ShaderProgram) GetAttribLoc(attribName string) int32 {
+	return gl.GetAttribLocation(sp.ID, gl.Str(attribName+"\x00"))
+}
+
+func (sp *ShaderProgram) Use() {
+	gl.UseProgram(sp.ID)
+}
+
+func (sp *ShaderProgram) Delete() {
+	gl.DeleteProgram(sp.ID)
+}

shaders/shaders.go

@@ -18,41 +18,6 @@ func (s Shader) Delete() {
 	gl.DeleteShader(s.ID)
 }
 
-type ShaderProgram struct {
-	ID           uint32
-	VertShaderID uint32
-	FragShaderID uint32
-}
-
-func (sp *ShaderProgram) AttachShader(shader Shader) {
-
-	gl.AttachShader(sp.ID, shader.ID)
-	switch shader.ShaderType {
-	case VertexShaderType:
-		sp.VertShaderID = shader.ID
-	case FragmentShaderType:
-		sp.FragShaderID = shader.ID
-	default:
-		logging.ErrLog.Println("Unknown shader type ", shader.ShaderType, " for ID ", shader.ID)
-	}
-}
-
-func (sp *ShaderProgram) Link() {
-
-	gl.LinkProgram(sp.ID)
-
-	if sp.VertShaderID != 0 {
-		gl.DeleteShader(sp.VertShaderID)
-	}
-	if sp.FragShaderID != 0 {
-		gl.DeleteShader(sp.FragShaderID)
-	}
-}
-
-func (sp *ShaderProgram) Delete() {
-	gl.DeleteProgram(sp.ID)
-}
-
 func NewShaderProgram() (ShaderProgram, error) {
 
 	id := gl.CreateProgram()