Implement vertical keystone and cylinder corrections

There's no configuration interface yet.

diff --git a/Makefile b/Makefile
index aa04a2b52f39313649a3dfa688fea8ee09bf3d15..5f0dc2101af554598386b1431efe31ae8d8f2481 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1,2 +1,2 @@
 geometrycompositor: source/main.c
-       gcc -o $@ $< -Wall -Wextra -Werror -std=c90 -pedantic -ggdb -lX11 -lXcomposite -lXdamage -lXext -lXrandr -lGL
+       gcc -o $@ $< -Wall -Wextra -Werror -std=c90 -pedantic -ggdb -lm -lX11 -lXcomposite -lXdamage -lXext -lXrandr -lGL

diff --git a/source/main.c b/source/main.c
index 13038c29ef83f6b8292a6e970edd06225c4de652..4beab4b93f10f9d092620335b64607db8344f754 100644 (file)
--- a/source/main.c
+++ b/source/main.c
@@ -3,6 +3,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
+#include <math.h>
 #include <X11/Xlib.h>
 #include <X11/extensions/Xcomposite.h>
 #include <X11/extensions/Xdamage.h>
@@ -33,6 +34,10 @@ typedef struct CompositedMonitor
        int y;
        unsigned width;
        unsigned height;
+       float keystone_vertical;
+       float cylinder_depth;
+       float vertical_center;
+       float perspective;
        unsigned vertex_buffer;
        unsigned index_buffer;
        unsigned vertex_array;
@@ -455,24 +460,49 @@ void update_monitor_vertices(CompositedScreen *screen, CompositedMonitor *monito
        unsigned short *index_data;
        unsigned x, y;
        unsigned i;
+       float aspect;
+       float cyl_w_sq;
+       float sin_ksv;
+       float cos_ksv;
 
        t = monitor->tessellation;
 
        data_size = (t+1)*(t+1)*4*sizeof(float);
        vertex_data = (float *)malloc(data_size);
+       aspect = (float)monitor->width/monitor->height;
+       cyl_w_sq = 0.25f-(0.5f-monitor->cylinder_depth)*(0.5f-monitor->cylinder_depth);
+       sin_ksv = monitor->keystone_vertical/sqrt(1.0f+monitor->keystone_vertical*monitor->keystone_vertical);
+       cos_ksv = sqrt(1.0f-sin_ksv*sin_ksv);
        for(y=0; y<=t; ++y)
                for(x=0; x<=t; ++x)
                {
-                       float xf, yf;
+                       float xf, yf, z, rz;
+                       float scale;
                        float *v;
 
                        xf = (float)x/t;
                        yf = (float)y/t;
+
                        v = vertex_data+(y*(t+1)+x)*4;
-                       v[0] = xf;
-                       v[1] = yf;
                        v[2] = (monitor->x+xf*monitor->width)/screen->width;
                        v[3] = (monitor->y+yf*monitor->height)/screen->height;
+
+                       z = sqrt(0.25f-(xf-0.5f)*(xf-0.5f)*4.0f*cyl_w_sq)-0.5f+monitor->cylinder_depth;
+                       if(monitor->keystone_vertical>0)
+                       {
+                               rz = (1.0f-yf)/aspect*sin_ksv+z*cos_ksv;
+                               yf = 1.0f-((1.0f-yf)*cos_ksv-z*aspect*sin_ksv);
+                               z = rz;
+                       }
+                       else if(monitor->keystone_vertical<0)
+                       {
+                               rz = z*cos_ksv-yf/aspect*sin_ksv;
+                               yf = yf*cos_ksv+z*aspect*sin_ksv;
+                               z = rz;
+                       }
+                       scale = monitor->perspective/(monitor->perspective+z);
+                       v[0] = 0.5f+(xf-0.5f)*scale;
+                       v[1] = monitor->vertical_center+(yf-monitor->vertical_center)*scale;
                }
        glBindBuffer(GL_ARRAY_BUFFER, monitor->vertex_buffer);
        glBufferData(GL_ARRAY_BUFFER, data_size, vertex_data, GL_STATIC_DRAW);
@@ -522,11 +552,16 @@ int initialize_monitor(Compositor *compositor, CompositedScreen *screen, Composi
        XRRFreeCrtcInfo(crtc);
        XRRFreeOutputInfo(output);
 
+       monitor->keystone_vertical = 0.0f;
+       monitor->cylinder_depth = 0.0f;
+       monitor->vertical_center = 0.5f;
+       monitor->perspective = 1.0f;
+
        glGenBuffers(2, buffers);
        monitor->vertex_buffer = buffers[0];
        monitor->index_buffer = buffers[1];
 
-       monitor->tessellation = 20;
+       monitor->tessellation = 50;
        update_monitor_vertices(screen, monitor);
        stride = 4*sizeof(float);