OpenGL Test

main.lua

require "os"
require "math"
require "glfw"
require "glua"

vertshade = [[
	#version 330

	layout(location = 0) in vec4 position;
	void main()
	{
	    gl_Position = position;
	}
]]

fragshade = [[
	#version 330

	out vec4 outputColor;
	void main()
	{
   		outputColor = vec4(1.0f, 0.0f, 0.0f, 1.0f);
	}
]]

function createShader(shadertype, source)
	shader = gl.CreateShader(shadertype)
	sources = alien.array("string", { source })
	gl.ShaderSource(shader, 1, sources.buffer, nil)
	gl.CompileShader(shader)
	
	statusbuf = alien.array("int", { 0 })
	gl.GetShaderiv(shader, GL_COMPILE_STATUS, statusbuf.buffer)

	if statusbuf[1] == 0 then
		return false
	end	

	return shader
end

function createProgram(vert, frag)
	program = gl.CreateProgram()
	gl.AttachShader(program, vert)
	gl.AttachShader(program, frag)
	gl.LinkProgram(program)

	statusbuf = alien.array("int", { 0 })
	gl.GetProgramiv(program, GL_LINK_STATUS, statusbuf.buffer)
	
	if statusbuf[1] == 0 then
		return false
	end
	
	return program
end

function prepareVertData()
	local vertData = alien.array("float",
	{
		0.75, 0.75, 0.0, 1.0,
	    0.75, -0.75, 0.0, 1.0,
    	-0.75, -0.75, 0.0, 1.0
	})

	buffersgenned = alien.array("int", { 0 })
	gl.GenBuffers(1, buffersgenned.buffer)

	gl.BindBuffer(GL_ARRAY_BUFFER, buffersgenned[1])
	gl.BufferData(GL_ARRAY_BUFFER, 12*4, vertData.buffer, GL_STATIC_DRAW)
	gl.BindBuffer(GL_ARRAY_BUFFER, 0)
	
end

function main()
	running = true

	if not glfw.Init() then
		return "Can't init GLFW."
	end
	
	glfw.OpenWindowHint(GLFW_WINDOW_NO_RESIZE, 1)
	glfw.OpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3)
	glfw.OpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 1)

	if not glfw.OpenWindow(800, 600, 0, 0, 0, 0, 0, 0, GLFW_WINDOW) then
		glfw.Terminate()
		return "Couldn't open window!"
	end

	glfw.SetWindowTitle("Windows man, windows.")

	prepareVertData()

	vertshader = createShader(GL_VERTEX_SHADER, vertshade)
	fragshader = createShader(GL_FRAGMENT_SHADER, fragshade)

	if not vertshader or not fragshader then return "Shader compilation failed." end

	program = createProgram(vertshader, fragshader)
	if not program then return "Program linking failed." end

	print(gl.GetError())
	while running do
		gl.ClearColor(0, 0, 0, 0)
		gl.Clear(GL_COLOR_BUFFER_BIT)
			gl.UseProgram(program)
			gl.BindBuffer(GL_ARRAY_BUFFER, buffersgenned[1])
			gl.EnableVertexAttribArray(0)
			gl.VertexAttribPointer(0, 4, GL_FLOAT, 0, 0, 0)

			gl.DrawArrays(GL_TRIANGLES, 0, 3)

			gl.DisableVertexAttribArray(0)
			gl.BindBuffer(GL_ARRAY_BUFFER, 0)
			gl.UseProgram(0)
		glfw.SwapBuffers()
		running = not glfw.GetKey(GLFW_KEY_SPACE)
	end

	glfw.CloseWindow()
	glfw.Terminate()

	return "Success. Clean exit."
end

print(main())