Hello all,
I am having some trouble with a simple test application. I am mixing
one of the nehe tutorials with the brick example from the OpenGL
orange book.
Here is my problem, all calls to glGetUniformLocation result in a
segmentation fault. I removed all calls to glGetUniformLocation, and
played around with guessing the appropriate values. Doing this I was
able to get the shader to render correctly, but is not a good way to
do things.
I am running Ubuntu 9.04 64bit
uname -a output: Linux starscream 2.6.28-11-generic #42-Ubuntu SMP Fri
Apr 17 01:58:03 UTC 2009 x86_64 GNU/Linux
Below I have listed the output from calling glGetString on my box, I
have also included my version of the program.
Any assistance would be appreciated.
Thanks,
Richard
GL_VENDOR: Tungsten Graphics, Inc
GL_RENDERER: Mesa DRI Intel(R) 965GM GEM 20090326 2009Q1 RC2
GL_VERSION: 2.0 Mesa 7.4
GL_EXTENSIONS: GL_ARB_depth_texture GL_ARB_draw_buffers
GL_ARB_fragment_program GL_ARB_fragment_program_shadow
GL_ARB_fragment_shader GL_ARB_multisample GL_ARB_multitexture
GL_ARB_occlusion_query GL_ARB_pixel_buffer_object
GL_ARB_point_parameters GL_ARB_point_sprite GL_ARB_shader_objects
GL_ARB_shading_language_100 GL_ARB_shadow GL_ARB_texture_border_clamp
GL_ARB_texture_compression GL_ARB_texture_cube_map
GL_ARB_texture_env_add GL_ARB_texture_env_combine
GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3
GL_ARB_texture_mirrored_repeat GL_ARB_texture_non_power_of_two
GL_ARB_texture_rectangle GL_ARB_transpose_matrix
GL_ARB_vertex_buffer_object GL_ARB_vertex_program GL_ARB_vertex_shader
GL_ARB_window_pos GL_EXT_abgr GL_EXT_bgra GL_EXT_blend_color
GL_EXT_blend_equation_separate GL_EXT_blend_func_separate
GL_EXT_blend_logic_op GL_EXT_blend_minmax GL_EXT_blend_subtract
GL_EXT_clip_volume_hint GL_EXT_cull_vertex
GL_EXT_compiled_vertex_array GL_EXT_copy_texture
GL_EXT_draw_range_elements GL_EXT_framebuffer_object GL_EXT_fog_coord
GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil
GL_EXT_packed_pixels GL_EXT_pixel_buffer_object
GL_EXT_point_parameters GL_EXT_polygon_offset GL_EXT_rescale_normal
GL_EXT_secondary_color GL_EXT_separate_specular_color
GL_EXT_shadow_funcs GL_EXT_stencil_wrap GL_EXT_subtexture
GL_EXT_texture GL_EXT_texture3D GL_EXT_texture_edge_clamp
GL_EXT_texture_env_add GL_EXT_texture_env_combine
GL_EXT_texture_env_dot3 GL_EXT_texture_filter_anisotropic
GL_EXT_texture_lod_bias GL_EXT_texture_object GL_EXT_texture_rectangle
GL_EXT_texture_sRGB GL_EXT_vertex_array
GL_3DFX_texture_compression_FXT1 GL_APPLE_client_storage
GL_APPLE_packed_pixels GL_ATI_blend_equation_separate
GL_ATI_texture_env_combine3 GL_ATI_separate_stencil
GL_IBM_rasterpos_clip GL_IBM_texture_mirrored_repeat
GL_INGR_blend_func_separate GL_MESA_pack_invert GL_MESA_ycbcr_texture
GL_MESA_window_pos GL_NV_blend_square GL_NV_light_max_exponent
GL_NV_point_sprite GL_NV_texture_rectangle GL_NV_texgen_reflection
GL_NV_vertex_program GL_NV_vertex_program1_1 GL_OES_read_format
GL_SGIS_generate_mipmap GL_SGIS_texture_border_clamp
GL_SGIS_texture_edge_clamp GL_SGIS_texture_lod GL_SGIX_depth_texture
GL_SUN_multi_draw_arrays
#--- pysqr.py ---------------------------
#!/usr/bin/python
import wx
from wx import glcanvas
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from OpenGL.GL.ARB.shader_objects import *
from OpenGL.GL.ARB.vertex_shader import *
from OpenGL.GL.ARB.fragment_shader import *
class GLFrame(wx.Frame):
"""A simple class for using OpenGL with wxPython."""
vert_src = """
uniform vec3 LightPosition;
const float SpecularContribution = 0.3;
const float DiffuseContribution = 1.0 - SpecularContribution;
varying float LightIntensity;
varying vec2 MCposition;
void main(void)
{
vec3 ecPosition = vec3 (gl_ModelViewMatrix * gl_Vertex);
vec3 tnorm = normalize(gl_NormalMatrix * gl_Normal);
vec3 lightVec = normalize(LightPosition - ecPosition);
vec3 reflectVec = reflect(-lightVec, tnorm);
vec3 viewVec = normalize(-ecPosition);
float diffuse = max(dot(lightVec, tnorm), 0.0);
float spec = 0.0;
if (diffuse > 0.0)
{
spec = max(dot(reflectVec, viewVec), 0.0);
spec = pow(spec, 16.0);
}
LightIntensity = DiffuseContribution * diffuse +
SpecularContribution * spec;
MCposition = gl_Vertex.xy;
gl_Position = ftransform();
}"""
frag_src = """
uniform vec3 BrickColor, MortarColor;
uniform vec2 BrickSize;
uniform vec2 BrickPct;
varying vec2 MCposition;
varying float LightIntensity;
void main(void)
{
vec3 color;
vec2 position, useBrick;
position = MCposition / BrickSize;
if (fract(position.y * 0.5) > 0.5)
position.x += 0.5;
position = fract(position);
useBrick = step(position, BrickPct);
color = mix(MortarColor, BrickColor, useBrick.x * useBrick.y);
color *= LightIntensity;
gl_FragColor = vec4 (color, 1.0);
}"""
def __init__(self, parent, id, title, pos=wx.DefaultPosition,
size=wx.DefaultSize, style=wx.DEFAULT_FRAME_STYLE,
name='frame'):
#
# Forcing a specific style on the window.
# Should this include styles passed?
style = wx.DEFAULT_FRAME_STYLE | wx.NO_FULL_REPAINT_ON_RESIZE
super(GLFrame, self).__init__(parent, id, title, pos, size, style, name)
self.GLinitialized = False
attribList = (glcanvas.WX_GL_RGBA, # RGBA
glcanvas.WX_GL_DOUBLEBUFFER, # Double Buffered
glcanvas.WX_GL_DEPTH_SIZE, 24) # 24 bit
#
# Create the canvas
self.canvas = glcanvas.GLCanvas(self, attribList=attribList)
#
# Set the event handlers.
self.canvas.Bind(wx.EVT_ERASE_BACKGROUND,
self.processEraseBackgroundEvent)
self.canvas.Bind(wx.EVT_SIZE, self.processSizeEvent)
self.canvas.Bind(wx.EVT_PAINT, self.processPaintEvent)
#
# Canvas Proxy Methods
def GetGLExtents(self):
"""Get the extents of the OpenGL canvas."""
return self.canvas.GetClientSize()
def SwapBuffers(self):
"""Swap the OpenGL buffers."""
self.canvas.SwapBuffers()
#
# wxPython Window Handlers
def processEraseBackgroundEvent(self, event):
"""Process the erase background event."""
pass # Do nothing, to avoid flashing on MSWin
def processSizeEvent(self, event):
"""Process the resize event."""
if self.canvas.GetContext():
# Make sure the frame is shown before calling SetCurrent.
self.Show()
self.canvas.SetCurrent()
size = self.GetGLExtents()
self.OnReshape(size.width, size.height)
self.canvas.Refresh(False)
event.Skip()
def processPaintEvent(self, event):
"""Process the drawing event."""
self.canvas.SetCurrent()
# This is a 'perfect' time to initialize OpenGL ... only if we need to
if not self.GLinitialized:
self.OnInitGL()
self.GLinitialized = True
self.OnDraw()
event.Skip()
#
# GLFrame OpenGL Event Handlers
def getUniLoc(self, program, name):
loc = glGetUniformLocation(program, name);
if (loc == -1):
print "No such uniform named ", name
return loc
def OnInitGL(self):
"""Initialize OpenGL for use in the window."""
print "GL_VENDOR: ", glGetString(GL_VENDOR)
print "GL_RENDERER: ", glGetString(GL_RENDERER)
print "GL_VERSION: ", glGetString(GL_VERSION)
print "GL_EXTENSIONS: ", glGetString(GL_EXTENSIONS)
glClearColor(0.0, 0.0, 0.0, 0.0)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0)
glMatrixMode( GL_MODELVIEW )
glLoadIdentity()
vert = glCreateShader(GL_VERTEX_SHADER)
frag = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(vert, self.vert_src)
glShaderSource(frag, self.frag_src)
glCompileShader(vert)
glCompileShader(frag)
program = glCreateProgram()
glAttachShader(program, vert)
glAttachShader(program, frag)
glValidateProgram(program)
glLinkProgram(program)
glUseProgram(program)
# Any of the following will cause a segmentation
# fault. (due to the call to glGetUniformLocation)
glUniform3f(self.getUniLoc(program, "BrickColor"), 1.0, 0.3, 0.2)
glUniform3f(self.getUniLoc(program, "MortarColor"), 0.85, 0.86, 0.84)
glUniform2f(self.getUniLoc(program, "BrickSize"), 0.30, 0.15)
glUniform2f(self.getUniLoc(program, "BrickPct"), 0.90, 0.85)
glUniform3f(self.getUniLoc(program, "LightPosition"), 0.0, 0.0, 4.0)
# These cause the shader to be rendered properly, but obviously is
# not the right way to do things. ;)
#glUniform3f(1, 1.0, 0.3, 0.2)
#glUniform3f(2, 0.85, 0.86, 0.84)
#glUniform2f(3, 0.30, 0.15)
#glUniform2f(4, 0.90, 0.85)
#glUniform3f(0, 0.0, 0.0, 4.0)
def OnReshape(self, width, height):
"""Reshape the OpenGL viewport based on the dimensions of the window."""
glViewport(0, 0, width, height)
def OnDraw(self, *args, **kwargs):
"Draw the window."
glClear(GL_COLOR_BUFFER_BIT)
glColor3f(1.0, 1.0, 1.0);
glBegin(GL_POLYGON);
glVertex2f(-0.5, -0.5);
glVertex2f(-0.5, 0.5);
glVertex2f(0.5, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
self.SwapBuffers()
def main():
app = wx.App()
frame = GLFrame(None, -1, 'GL Window')
frame.Show()
app.MainLoop()
app.Destroy()
if __name__ == "__main__":
main()
# --- end of pysqr.py ------------------------
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