RubyでGLSLしてみた

RubyでOpenGLをやってみるとRuby/Qt/OpenGL で GLSL を使ってみるを参考にRubyでGLSLしてみた。シェーダーでは単純に赤く塗りつぶしてるだけなので立体感が無い状態だけど、そのうちLambertなりPhongあたりをやる予定。

。シェーダーのコンパイル時のエラーメッセージの取得方法がまだわかってなかったり。以下ソースコード

tea.rb

require "rubygems"
require "opengl"
require "glut"

class Teapot
    def reshape(w,h)
        GL.Viewport(0,0,w,h)

        GL.MatrixMode(GL::GL_PROJECTION)
        GL.LoadIdentity()
        GLU.Perspective(45.0, w.to_f()/h.to_f(), 0.1, 100.0)
    end

    def display()
        GL.MatrixMode(GL::GL_MODELVIEW)
        GL.LoadIdentity()
        GLU.LookAt(0.5, 1.5, 2.5, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0)

        GL.ClearColor(0.0, 0.0, 0.0, 1.0)
        GL.Clear(GL::GL_COLOR_BUFFER_BIT | GL::GL_DEPTH_BUFFER_BIT)

        GL.Rotate(@rotX, 1, 0, 0)
        GL.Rotate(@rotY, 0, 1, 0)
        
        GL.UseProgram(@program);
        GLUT.SolidTeapot(0.5)

        GLUT.SwapBuffers()
    end

    def mouse(button,state,x,y)
        if button == GLUT::GLUT_LEFT_BUTTON && state == GLUT::GLUT_DOWN then
            @start_x = x
            @start_y = y
            @drag_flg = true
        elsif state == GLUT::GLUT_UP then
            @drag_flg = false
        end
    end

    def motion(x,y)
        if @drag_flg then
            dx = x - @start_x
            dy = y - @start_y

            @rotY += dx
            @rotY = @rotY % 360

            @rotX += dy
            @rotX = @rotX % 360
        end
        @start_x = x
        @start_y = y
        GLUT.PostRedisplay()
    end

    def initialize()
        @start_x = 0
        @start_y = 0
        @rotY = 0
        @rotX = 0
        @drag_flg = false
        GLUT.InitWindowPosition(100, 100)
        GLUT.InitWindowSize(300,300)
        GLUT.Init()
        GLUT.InitDisplayMode(GLUT::GLUT_DOUBLE | GLUT::GLUT_RGB | GLUT::GLUT_DEPTH)
        GLUT.CreateWindow("Ruby de GLSL")

        GL.Enable(GL::GL_DEPTH_TEST)
        GL.FrontFace(GL::GL_CW)
        GL.Enable(GL::GL_AUTO_NORMAL)
        GL.Enable(GL::GL_NORMALIZE)
        GL.Enable(GL::GL_DEPTH_TEST)
        GL.DepthFunc(GL::GL_LESS)

        @program = create_program("tea.vert", "tea.frag")

        GLUT.ReshapeFunc(method(:reshape).to_proc())
        GLUT.DisplayFunc(method(:display).to_proc())
        GLUT.MouseFunc(method(:mouse).to_proc())
        GLUT.MotionFunc(method(:motion).to_proc())
    end
    
    def create_program(vert_name, frag_name)
        program = GL.CreateProgram()
        
        vert_shader = create_shader(vert_name, GL_VERTEX_SHADER)
        frag_shader = create_shader(frag_name, GL_FRAGMENT_SHADER)
        
        GL.AttachShader(program, vert_shader)
        GL.AttachShader(program, frag_shader)
        GL.LinkProgram(program)
        GL.GetProgramiv(program, GL_LINK_STATUS)

        GL.DeleteShader(vert_shader)
        GL.DeleteShader(frag_shader)

        return program
    end

    def create_shader(file_name, type)
        shader = GL.CreateShader(type)
        
        File.open(file_name, "rb") { |file|
            GL.ShaderSource(shader, file.read())
            GL.CompileShader(shader)
            GL.GetShaderiv(shader, GL_COMPILE_STATUS)
        }
        
        return shader
    end

    def start()
        GLUT.MainLoop()
    end
end

Teapot.new().start()

tea.vert

void main(void)
{
    gl_Position = ftransform();
}

tea.frag

void main (void)
{
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}