Add polygon sorting to sorting example

Sorting works!
TODO: tessellations

diff --git a/examples/sorting/sort.c b/examples/sorting/sort.c
index 701ced197161044842ef484c26f0e656f07d1696..745e1fc28afe09c589fa32aee4f16eb0f4125bcf 100644 (file)
--- a/examples/sorting/sort.c
+++ b/examples/sorting/sort.c
@@ -3,17 +3,90 @@
 #include <gdk/gdkkeysyms.h>
 #include <GL/gl.h>
 #include <GL/glu.h>
+#include <stdlib.h>
 
-guint tex, texl, texr;
+typedef struct {
+       gfloat xyz[3];
+       gfloat color[4];
+} __attribute__ ((packed)) vert_t;
 
-gboolean on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer _)
+static int sort_cmp(const void *a, const void *b)
 {
-       if (event->keyval == GDK_q)
-               gtk_main_quit();
-       return FALSE;
+       vert_t *a_verts = (vert_t*)(((gfloat*)a)+2);
+       vert_t *b_verts = (vert_t*)(((gfloat*)b)+2);
+       gfloat a_sum = a_verts[0].xyz[2] + a_verts[1].xyz[2] + a_verts[2].xyz[2];
+       gfloat b_sum = b_verts[0].xyz[2] + b_verts[1].xyz[2] + b_verts[2].xyz[2];
+       return a_sum == b_sum ? 0 :
+              a_sum <  b_sum ? 1 : -1;
+}
+
+static gfloat *sort_start()
+{
+       int size = 1000000;
+       gfloat *data = g_new0(gfloat, size);
+       glFeedbackBuffer(size, GL_3D_COLOR, data);
+       glRenderMode(GL_FEEDBACK);
+       g_print("1st = %f\n", data[0]);
+       return data;
+}
+
+static void sort_end(gfloat *data)
+{
+       int vertsize = sizeof(vert_t)/sizeof(gfloat);
+       int count = glRenderMode(GL_RENDER);
+
+       /* Set up screen coords */
+       gint view[4];
+       glGetIntegerv(GL_VIEWPORT, view);
+
+       glMatrixMode(GL_PROJECTION);
+       glLoadIdentity();
+       glOrtho(view[0],view[2], view[1],view[3], -10,10);
+
+       glMatrixMode(GL_MODELVIEW);
+       glLoadIdentity();
+       glDisable(GL_LIGHTING);
+
+       /* Sort the vertexes (this only works with all-triangles */
+       int trisize = 2*sizeof(gfloat) + 3*sizeof(vert_t);
+       int ntris   = count / trisize;
+       g_print("%d, %d, %d\n", sizeof(gfloat), trisize, ntris);
+       qsort(data, ntris*4, trisize, sort_cmp);
+
+       /* Draw the data */
+       for (int i = 0; i < count;) {
+               gfloat token = data[i++];
+               if (token == GL_POLYGON_TOKEN) {
+                       gfloat n = data[i++];
+                       vert_t *verts = (vert_t*)&data[i];
+                       i += n*vertsize;
+                       //g_print("GL_POLYGON_TOKEN: %f\n", n);
+
+                       /* Draw triangle */
+                       glBegin(GL_TRIANGLES);
+                       for (int j = 0; j < n; j++) {
+                               //g_print("\t%f, %f, %f\n",
+                               //      verts[j].xyz[0],
+                               //      verts[j].xyz[1],
+                               //      verts[j].xyz[2]);
+                               glColor4fv(verts[j].color);
+                               glVertex3fv(verts[j].xyz);
+                       }
+                       glEnd();
+
+                       /* Draw line */
+                       glColor4f(1,1,1,1);
+                       glBegin(GL_LINE_LOOP);
+                       for (int j = 0; j < n; j++)
+                               glVertex3fv(verts[j].xyz);
+                       glEnd();
+               } else {
+                       g_error("Unknown token: %f\n", token);
+               }
+       }
 }
 
-gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
+static gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
 {
        //glClearColor(0.5, 0.5, 1.0, 1.0);
        glClearColor(0.0, 0.0, 0.0, 0.0);
@@ -43,22 +116,24 @@ gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
        /* Set up projection */
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
-       glOrtho(1,-1, -1,1, -10,10);
+       glOrtho(1,-1, -0.7,0.7, -10,10);
 
        /* Draw teapots */
        glMatrixMode(GL_MODELVIEW);
 
+       gfloat *data = sort_start();
        glLoadIdentity();
-       glTranslatef(-0.2, -0.2, -2);
+       glTranslatef(0.05, 0.05, -2);
        glRotatef(30, 1, -1, -0.2);
-       glColor4f(0.6, 0.6, 0.4, 0.5);
+       glColor4f(1.0, 0.2, 0.2, 0.6);
        gdk_gl_draw_teapot(TRUE, 0.5);
 
        glLoadIdentity();
-       glTranslatef(0.2, 0.2, -2);
+       glTranslatef(-0.2, -0.05, -2);
        glRotatef(30, 1, -1, -0.2);
-       glColor4f(0.6, 0.6, 0.4, 0.5);
+       glColor4f(0.2, 0.2, 1.0, 0.6);
        gdk_gl_draw_teapot(TRUE, 0.5);
+       sort_end(data);
 
        /* Flush */
        GdkGLDrawable *gldrawable = gdk_gl_drawable_get_current();
@@ -69,7 +144,7 @@ gboolean on_expose(GtkWidget *drawing, GdkEventExpose *event, gpointer _)
        return FALSE;
 }
 
-gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
+static gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
 {
        glViewport(0, 0,
                drawing->allocation.width,
@@ -77,6 +152,13 @@ gboolean on_configure(GtkWidget *drawing, GdkEventConfigure *event, gpointer _)
        return FALSE;
 }
 
+static gboolean on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer _)
+{
+       if (event->keyval == GDK_q)
+               gtk_main_quit();
+       return FALSE;
+}
+
 int main(int argc, char **argv)
 {
        gtk_init(&argc, &argv);