For some reason I'm unable to pass floats to shaders. Whatever values i use for the second argument in glUniform1f the float variable it sets inside the shader stays zero. I'm using version 100.14.11 of the drivers on a 8800GTS 320mb.
This test program should draw a yellow triangle, but only draws a green one because glUniform1f fails to set var1 to 1.0.
Code:
#include <GL/gl.h>
#include <GL/glx.h>
#include <stdio.h>
#include <stdlib.h>
GLuint program = 0;
static void redraw( Display *dpy, Window w )
{
printf("Redraw event\n");
glClear( GL_COLOR_BUFFER_BIT );
glTranslatef(-1.5f,0.0f,-6.0f);
glLoadIdentity();
glUseProgram(program);
glUniform1f(glGetUniformLocation(program, "var1"), 1.0f);
glUniform1i(glGetUniformLocation(program, "var2"), 1);
glBegin(GL_TRIANGLES);
glVertex3f( 0.0f, 1.0f, 0.0f);
glVertex3f(-1.0f,-1.0f, 0.0f);
glVertex3f( 1.0f,-1.0f, 0.0f);
glEnd();
glXSwapBuffers( dpy, w );
}
static void resize( unsigned int width, unsigned int height )
{
printf("Resize event\n");
glViewport( 0, 0, width, height );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
}
static Window make_rgb_db_window( Display *dpy,
unsigned int width, unsigned int height )
{
int attrib[] = { GLX_RGBA,
GLX_RED_SIZE, 1,
GLX_GREEN_SIZE, 1,
GLX_BLUE_SIZE, 1,
GLX_DOUBLEBUFFER,
None };
int scrnum;
XSetWindowAttributes attr;
unsigned long mask;
Window root;
Window win;
GLXContext ctx;
XVisualInfo *visinfo;
scrnum = DefaultScreen( dpy );
root = RootWindow( dpy, scrnum );
visinfo = glXChooseVisual( dpy, scrnum, attrib );
if (!visinfo) {
printf("Error: couldn't get an RGB, Double-buffered visual\n");
exit(1);
}
/* window attributes */
attr.background_pixel = 0;
attr.border_pixel = 0;
attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
attr.event_mask = StructureNotifyMask | ExposureMask;
mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
win = XCreateWindow( dpy, root, 0, 0, width, height,
0, visinfo->depth, InputOutput,
visinfo->visual, mask, &attr );
ctx = glXCreateContext( dpy, visinfo, NULL, True );
if (!ctx) {
printf("Error: glXCreateContext failed\n");
exit(1);
}
glXMakeCurrent( dpy, win, ctx );
return win;
}
static void event_loop( Display *dpy )
{
XEvent event;
while (1) {
XNextEvent( dpy, &event );
switch (event.type) {
case Expose:
redraw( dpy, event.xany.window );
break;
case ConfigureNotify:
resize( event.xconfigure.width, event.xconfigure.height );
break;
}
}
}
static const char *shadercode =
"uniform float var1;\
uniform int var2;\
\
void main(void)\
{\
gl_FragColor = vec4(var1, var2, 0.0, 1.0);\
}";
int main( int argc, char *argv[] )
{
Display *dpy;
Window win;
GLuint shader;
dpy = XOpenDisplay(NULL);
win = make_rgb_db_window( dpy, 300, 300 );
shader = glCreateShader(GL_FRAGMENT_SHADER);
program = glCreateProgram();
glShaderSource(shader, 1, &shadercode, NULL);
glCompileShader(shader);
glAttachShader(program, shader);
glLinkProgram(program);
glDeleteShader(shader);
XMapWindow( dpy, win );
event_loop( dpy );
return 0;
}