pixie/examples/realtime_glut.nim
2021-10-04 15:08:36 -07:00

79 lines
2.4 KiB
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
let linerGradient = newPaint(pkGradientLinear)
linerGradient.gradientHandlePositions.add(vec2(0, 0))
linerGradient.gradientHandlePositions.add(vec2(0, 256))
linerGradient.gradientStops.add(
ColorStop(color: color(0, 0, 0, 1), position: 0))
linerGradient.gradientStops.add(
ColorStop(color: color(1, 1, 1, 1), position: 1))
ctx.fillStyle = linerGradient
ctx.fillRect(0, 0, 256, 256)
let radialGradient = newPaint(pkGradientRadial)
radialGradient.gradientHandlePositions.add(vec2(128, 128))
radialGradient.gradientHandlePositions.add(vec2(256, 128))
radialGradient.gradientHandlePositions.add(vec2(128, 256))
radialGradient.gradientStops.add(
ColorStop(color: color(1, 1, 1, 1), position: 0))
radialGradient.gradientStops.add(
ColorStop(color: color(0, 0, 0, 1), position: 1))
ctx.fillStyle = radialGradient
ctx.fillCircle(circle(
vec2(128.0, 128.0 + sin(float32(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()