From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 12 Dec 2015 14:37:53 +0000 (+0200)
Subject: Implement vertical keystone and cylinder corrections
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=77803dd85ecfa2cc3c7265f8f64c535064181eed;p=geometrycompositor.git

Implement vertical keystone and cylinder corrections

There's no configuration interface yet.
---

diff --git a/Makefile b/Makefile
index aa04a2b..5f0dc21 100644
--- 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 13038c2..4beab4b 100644
--- 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);