pixie/examples/realtime_glut.nim
treeform f4d144e21c
Add real-time examples. (#205)
* Add real-time examples.
* Add readme.
2021-05-24 10:49:09 -07:00

77 lines
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Nim

## This example show how to have real time pixie using glut API.
import math, opengl, opengl/glu, opengl/glut, pixie
let
w: int32 = 256
h: int32 = 256
var
screen = newImage(w, h)
ctx = newContext(screen)
frameCount = 0
proc display() {.cdecl.} =
## Called every frame by GLUT
# draw shiny sphere on gradient background
var linerGradient = Paint(kind: pkGradientLinear)
linerGradient.gradientHandlePositions.add(vec2(0, 0))
linerGradient.gradientHandlePositions.add(vec2(0, 256))
linerGradient.gradientStops.add(
ColorStop(color: rgbx(0, 0, 0, 255), position: 0))
linerGradient.gradientStops.add(
ColorStop(color: rgbx(255, 255, 255, 255), position: 1))
ctx.fillStyle = linerGradient
ctx.fillRect(0, 0, 256, 256)
var radialGradient = Paint(kind: pkGradientRadial)
radialGradient.gradientHandlePositions.add(vec2(128, 128))
radialGradient.gradientHandlePositions.add(vec2(256, 128))
radialGradient.gradientHandlePositions.add(vec2(128, 256))
radialGradient.gradientStops.add(
ColorStop(color: rgbx(255, 255, 255, 255), position: 0))
radialGradient.gradientStops.add(
ColorStop(color: rgbx(0, 0, 0, 255), position: 1))
ctx.fillStyle = radialGradient
ctx.fillCircle(vec2(128.0, 128.0 + sin(float(frameCount)/10.0) * 20), 76.8)
# update texture with new pixels from surface
var dataPtr = ctx.image.data[0].addr
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, GLsizei w, GLsizei h, GL_RGBA,
GL_UNSIGNED_BYTE, dataPtr)
# draw a quad over the whole screen
glClear(GL_COLOR_BUFFER_BIT)
glBegin(GL_QUADS)
glTexCoord2d(0.0, 0.0); glVertex2d(-1.0, +1.0)
glTexCoord2d(1.0, 0.0); glVertex2d(+1.0, +1.0)
glTexCoord2d(1.0, 1.0); glVertex2d(+1.0, -1.0)
glTexCoord2d(0.0, 1.0); glVertex2d(-1.0, -1.0)
glEnd()
glutSwapBuffers()
inc frameCount
glutPostRedisplay() # ask glut to draw next frame
glutInit()
glutInitDisplayMode(GLUT_DOUBLE)
glutInitWindowSize(w, h)
discard glutCreateWindow("GLUT/Pixie")
glutDisplayFunc(display)
loadExtensions()
# allocate a texture and bind it
var dataPtr = ctx.image.data[0].addr
glTexImage2D(GL_TEXTURE_2D, 0, 3, GLsizei w, GLsizei h, 0, GL_RGBA,
GL_UNSIGNED_BYTE, dataPtr)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
glEnable(GL_TEXTURE_2D)
glutMainLoop()