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ysgard/matrix.vertexshader

Created March 24, 2013 23:45
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Trying to pass a matrix to a matrix uniform in the shader. (http://arcsynthesis.org/gltut/Positioning/Tut04%20The%20Matrix%20Has%20You.html)
Raw
matrix.vertexshader
layout(location = 0) in vec4 position;
layout(location = 1) in vec4 color;
smooth out vec4 theColor;
uniform vec2 offset;
uniform mat4 perspectiveMatrix;
void main() {
vec4 cameraPos = position + vec4(offset.x, offset.y, 0.0, 0.0);
gl_Position = perspectiveMatrix * cameraPos;
theColor = color;
}
Raw
perspectiveprism.go
/*
Perspective Prism
*/
package main
import (
"fmt"
gl "github.com/chsc/gogl/gl33"
"github.com/go-gl/glfw"
"os"
"runtime"
"unsafe"
)
const (
Width = 500
Height = 500
Title = "Perspective Prism"
)
// Shader program and uniorms
var currentShader gl.Uint
var offsetUniform gl.Int
var perspectiveMatrixUnif gl.Int
// Shader ilenames
var shaders = []string{
"shaders/matrix.vertexshader",
"shaders/orthographic.fragmentshader",
}
// Vertex arrays and buffers
var vertexBufferObject gl.Uint
var vao gl.Uint
var vertexData = []gl.Float{
0.25, 0.25, -1.25, 1.0,
0.25, -0.25, -1.25, 1.0,
-0.25, 0.25, -1.25, 1.0,
0.25, -0.25, -1.25, 1.0,
-0.25, -0.25, -1.25, 1.0,
-0.25, 0.25, -1.25, 1.0,
0.25, 0.25, -2.75, 1.0,
-0.25, 0.25, -2.75, 1.0,
0.25, -0.25, -2.75, 1.0,
0.25, -0.25, -2.75, 1.0,
-0.25, 0.25, -2.75, 1.0,
-0.25, -0.25, -2.75, 1.0,
-0.25, 0.25, -1.25, 1.0,
-0.25, -0.25, -1.25, 1.0,
-0.25, -0.25, -2.75, 1.0,
-0.25, 0.25, -1.25, 1.0,
-0.25, -0.25, -2.75, 1.0,
-0.25, 0.25, -2.75, 1.0,
0.25, 0.25, -1.25, 1.0,
0.25, -0.25, -2.75, 1.0,
0.25, -0.25, -1.25, 1.0,
0.25, 0.25, -1.25, 1.0,
0.25, 0.25, -2.75, 1.0,
0.25, -0.25, -2.75, 1.0,
0.25, 0.25, -2.75, 1.0,
0.25, 0.25, -1.25, 1.0,
-0.25, 0.25, -1.25, 1.0,
0.25, 0.25, -2.75, 1.0,
-0.25, 0.25, -1.25, 1.0,
-0.25, 0.25, -2.75, 1.0,
0.25, -0.25, -2.75, 1.0,
-0.25, -0.25, -1.25, 1.0,
0.25, -0.25, -1.25, 1.0,
0.25, -0.25, -2.75, 1.0,
-0.25, -0.25, -2.75, 1.0,
-0.25, -0.25, -1.25, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0,
0.8, 0.8, 0.8, 1.0,
0.8, 0.8, 0.8, 1.0,
0.8, 0.8, 0.8, 1.0,
0.8, 0.8, 0.8, 1.0,
0.8, 0.8, 0.8, 1.0,
0.8, 0.8, 0.8, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
0.5, 0.5, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0,
0.0, 1.0, 1.0, 1.0,
}
func glfwInitWindow() {
// Initialize glfw
glfw.Init()
// Set some basic params or the window
glfw.OpenWindowHint(glfw.FsaaSamples, 4) // 4x antialiasing
glfw.OpenWindowHint(glfw.OpenGLVersionMajor, 3)
glfw.OpenWindowHint(glfw.OpenGLVersionMinor, 2)
// Core, not compat
glfw.OpenWindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
// Open a window and initialize its OpenGL content
if err := glfw.OpenWindow(Width, Height, 0, 0, 0, 0, 32, 0, glfw.Windowed); err != nil {
fmt.Fprintf(os.Stderr, "glfw.OpenWindow failed: %s\n", err)
os.Exit(1)
}
// Set the Window title
glfw.SetWindowTitle(Title)
// Make sure we can capture the escape key
glfw.Enable(glfw.StickyKeys)
}
// glInit - initialize OpenGL context and vertex arrays
func glInit() {
gl.Init()
// Load the shaders
currentShader = CreateShaderProgram(shaders)
offsetUniform = gl.GetUniformLocation(currentShader, gl.GLString("offset"))
perspectiveMatrixUnif = gl.GetUniformLocation(currentShader, gl.GLString("perspectiveMatrixUnif"))
gl.UseProgram(currentShader)
// Initialize the uniforms
var fFrustumScale = gl.Float(1.0)
var fzNear = gl.Float(0.5)
var fzFar = gl.Float(3.0)
theMatrix := make([]gl.Float, 16)
theMatrix[0] = fFrustumScale
theMatrix[5] = fFrustumScale
theMatrix[10] = (fzFar + fzNear) / (fzNear - fzFar)
theMatrix[14] = (2 * fzFar * fzNear) / (fzNear - fzFar)
theMatrix[11] = -1.0
// var theMatrix = [16]gl.Float{
// fFrustumScale, 0, 0, 0,
// 0, fFrustumScale, 0, 0,
// 0, 0, (fzFar + fzNear) / (fzNear - fzFar), -1.0,
// 0, 0, (2 * fzFar * fzNear) / (fzNear - fzFar), 0,
// }
gl.UniformMatrix4fv(perspectiveMatrixUnif, 1, gl.FALSE, &theMatrix[0])
gl.UseProgram(0)
}
// Create necessary buffers
func initializeVertexBuffer() {
gl.GenBuffers(1, &vertexBufferObject)
gl.BindBuffer(gl.ARRAY_BUFFER, vertexBufferObject)
buflen := unsafe.Sizeof(vertexData[0]) * (uintptr)(len(vertexData))
gl.BufferData(gl.ARRAY_BUFFER,
gl.Sizeiptr(buflen),
gl.Pointer(&vertexData[0]),
gl.STATIC_DRAW)
gl.BindBuffer(gl.ARRAY_BUFFER, 0)
}
// Called after window creation and OpenGL initialization
// Once before main loop
func programInit() {
initializeVertexBuffer()
// Init vertex arrays
gl.GenVertexArrays(1, &vao)
gl.BindVertexArray(vao)
// Cull faces
gl.Enable(gl.CULL_FACE)
gl.CullFace(gl.BACK)
// Winding order - determine which face is the 'front'
// of the triangle. In this case, the vertices were
// defined in vertexData such on order that a clockwise
// winding defines their front.
gl.FrontFace(gl.CW)
// Set the key handler for the main loop
glfw.SetKeyCallback(keyboard)
// Set the resize handler
glfw.SetWindowSizeCallback(reshape)
}
// display - render an OpenGL frame, this function should be
// called once per frame
func display() {
// Clear the background, then draw black
gl.ClearColor(0.0, 0.0, 0.0, 0.0)
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.UseProgram(currentShader)
// Pass a vector of two floats to the shader using
// the offsetUniform handle
gl.Uniform2f(offsetUniform, 0.5, 0.5)
// Append the
offset := (len(vertexData) / 2) * 4
gl.BindBuffer(gl.ARRAY_BUFFER, vertexBufferObject)
gl.EnableVertexAttribArray(0)
gl.EnableVertexAttribArray(1)
gl.VertexAttribPointer(0, 4, gl.FLOAT, gl.FALSE, 0, nil)
gl.VertexAttribPointer(1, 4, gl.FLOAT, gl.FALSE, 0,
gl.Offset(nil, (uintptr)(offset)))
gl.DrawArrays(gl.TRIANGLES, 0, 36)
gl.DisableVertexAttribArray(0)
gl.DisableVertexAttribArray(1)
gl.UseProgram(0)
glfw.SwapBuffers()
}
// Called whenever the window is resized. The new window size is
// is given in pixels. This is an opportunity to call glViewport
// or glScissor to keep up with the change in size.
func reshape(w, h int) {
gl.Viewport(0, 0, (gl.Sizei)(w), (gl.Sizei)(h))
}
func shutdown() {
// Delete all buffers, shut down glfw
gl.DeleteBuffers(1, &vertexBufferObject)
gl.DeleteProgram(currentShader)
gl.DeleteVertexArrays(1, &vao)
glfw.Terminate()
}
// Called whenever a key is pressed or released. Esc terminates the
// program.
func keyboard(key, state int) {
if state == glfw.KeyPress {
switch key {
case glfw.KeyEsc:
shutdown()
}
}
return
}
// Main loop
func main() {
// Sit. Down. Good boy.
runtime.LockOSThread()
// Initialize subsystems
glfwInitWindow()
glInit()
programInit()
// Main loop. Run until it dies, or we find someone better.
for glfw.WindowParam(glfw.Opened) == 1 {
display()
}
}
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