OpenGL pixel shader: Difference between revisions
Added Kotlin
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=={{header|Kotlin}}==
{{trans|C}}
{{libheader|freeglut}}
{{libheader|GLEW}}
{{works with|Ubuntu 14.04}}
Assuming that freeglut and GLEW are already installed on your system in the default location(s), you first need to build opengl2.klib using the following .def file and the cinterop tool:
<pre>
// opengl2.def
headers = /usr/include/GL/glew.h /usr/include/GL/glut.h /usr/include/GL/glext.h
compilerOpts = -I/usr/include
linkerOpts = -L/usr/lib/x86_64-linux-gnu -lglut -lGLEW -lGL -lGLU
</pre>
You then need to compile the following Kotlin program, linking against opengl2.klib, and run the resulting .kexe file to view the rotating triangle.
<lang scala>// Kotlin Native v0.6
import kotlinx.cinterop.*
import opengl2.*
var rMod = 0
var angle = 0f
fun render() {
glClear(GL_COLOR_BUFFER_BIT)
__glewUniform1f!!(rMod, rand() / RAND_MAX.toFloat())
glLoadIdentity()
glRotatef(angle, angle * 0.1f, 1f, 0f)
glBegin(GL_TRIANGLES)
glVertex3f(-1f, -0.5f, 0f)
glVertex3f(0f, 1f, 0f)
glVertex3f(1f, 0f, 0f)
glEnd()
angle += 0.02f
glutSwapBuffers()
}
fun setShader() {
val f =
"varying float x, y, z;" +
"uniform float r_mod;" +
"float rand(float s, float r) { return mod(mod(s, r + r_mod) * 112341, 1); }" +
"void main() {" +
" gl_FragColor = vec4(rand(gl_FragCoord.x, x), " +
"rand(gl_FragCoord.y, y), rand(gl_FragCoord.z, z), 1);" +
"}"
val v =
"varying float x, y, z;" +
"void main() {" +
" gl_Position = ftransform();" +
" x = gl_Position.x; y = gl_Position.y; z = gl_Position.z;" +
" x += y; y -= x; z += x - y;" +
"}"
val vs = __glewCreateShader!!(GL_VERTEX_SHADER)
val ps = __glewCreateShader!!(GL_FRAGMENT_SHADER)
memScoped {
val fp = allocPointerTo<ByteVar>()
fp.value = f.cstr.getPointer(memScope)
__glewShaderSource!!(ps, 1, fp.ptr, null)
val vp = allocPointerTo<ByteVar>()
vp.value = v.cstr.getPointer(memScope)
__glewShaderSource!!(vs, 1, vp.ptr, null)
__glewCompileShader!!(vs)
__glewCompileShader!!(ps)
val prog = __glewCreateProgram!!()
__glewAttachShader!!(prog, ps)
__glewAttachShader!!(prog, vs)
__glewLinkProgram!!(prog)
__glewUseProgram!!(prog)
val sp = allocPointerTo<ByteVar>()
sp.value = "r_mod".cstr.getPointer(memScope)
rMod = __glewGetUniformLocation!!(prog, sp.value)
}
}
fun main(args: Array<String>) {
memScoped {
val argc = alloc<IntVar>().apply { value = 0 }
glutInit(argc.ptr, null)
}
glutInitDisplayMode(GLUT_DOUBLE or GLUT_RGB)
glutInitWindowSize(200, 200)
glutCreateWindow("Stuff")
glutIdleFunc(staticCFunction(::render))
glewInit()
if (glewIsSupported("GL_VERSION_2_0") == 0.toByte()) {
println("GL 2.0 unsupported\n")
return
}
setShader()
glutMainLoop()
}</lang>
=={{header|Racket}}==
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