Added ability to take screenshots, since it's basically impossible to…

… take one normally and get it sync'd right.

Makefile

@@ -1,4 +1,4 @@
-SRC = src/main.cpp src/scene.cpp
+SRC = src/main.cpp src/scene.cpp src/screenshot.cpp
 OBJ = $(SRC:.cpp=.o)
 OUT = 3dvgl
 

src/main.cpp

@@ -9,6 +9,7 @@ extern "C" {
 
 #include "scene.h"
 #include "stereo_helper.h"
+#include "screenshot.h"
 
 // global width and height of the window
 int GW = 800;
@@ -20,18 +21,40 @@ struct nvstusb_context *nv_ctx = NULL;
 // 3D camera from stereo helper
 StereoHelper::Camera cam;
 
+// forces a particular eye to be displayed (for debugging)
+// 0 = normal swapping, 1 = left always, 2 = right always
+int force_eye = 0;
+
+// controls whether or not the pulsar is rotating
+bool rotation = true;
+
 void draw(int eye) {
-    static float rotation = 0.0f;
+    static float angle = 0.0f;
 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
+    int show = 0;
+    switch (force_eye) {
+        case 0:
+            show = eye;
+            break;
+
+        case 1:
+            show = 1;
+            break;
+
+        case 2:
+            show = 0;
+            break;
+    }
+
     // do the camera projection
-    StereoHelper::ProjectCamera(cam, (float)GW / GH, eye);
+    StereoHelper::ProjectCamera(cam, (float)GW / GH, show);
 
     // draw Paul Bourke's test scene "pulsar"
-    rotation += 1.0f;
+    if (rotation) angle += 1.0f;
     PaulBourke::MakeLighting();
-    PaulBourke::MakeGeometry(rotation);
+    PaulBourke::MakeGeometry(angle);
 }
 
 void idle() {
@@ -51,9 +74,24 @@ void idle() {
     struct nvstusb_keys k;
     nvstusb_get_keys(nv_ctx, &k);
 
-    if (k.toggled3D) printf("TOGGLE!\n");
-    if (k.deltaWheel != 0) printf("DELTA WHEEL %d\n", k.deltaWheel);
-    if (k.pressedDeltaWheel != 0) printf("PRESSED DELTA WHEEL %d\n", k.pressedDeltaWheel);
+    // the 3D button on the IR emitter controls toggling the rotation on and
+    // off
+    if (k.toggled3D) {
+        rotation = !rotation;
+        printf("Toggled rotation.\n");
+    }
+
+    // the wheel on the back adjusts the focal length of the camera (and
+    // interoccular distance, since we want to maintain IOD = 1/30th of the
+    // focal length)
+    if (k.deltaWheel != 0) {
+        cam.focal += k.deltaWheel;
+        cam.iod = cam.focal / 30.0f;
+        printf("Set camera focal length to %f.\n", cam.focal);
+    }
+
+    // you can also use k.pressedDeltaWheel, which reports the amount the wheel
+    // moves while the 3D button is pressed
 }
 
 void keyboard(unsigned char key, int x, int y) {
@@ -70,6 +108,23 @@ void keyboard(unsigned char key, int x, int y) {
                 cam.type = StereoHelper::TOE_IN;
                 printf("Using toe-in stereo camera.\n");
             }
+            break;
+
+        case 'f': case 'F': // force eye
+            force_eye = (force_eye + 1) % 3;
+            if (force_eye == 0) {
+                printf("Swapping eyes normally.\n");
+            } else if (force_eye == 1) {
+                printf("Forcing left eye always.\n");
+            } else {
+                printf("Forcing right eye always.\n");
+            }
+            break;
+
+        case 's': case 'S': // take screenshot
+            Screenshot::Screenshot(0, 0, GW, GH, "screenshot.tga");
+            printf("Wrote frame buffer to screenshot.tga.\n");
+            break;
     }
 }
 
@@ -112,6 +167,7 @@ int main(int argc, char *argv[]) {
     glShadeModel(GL_SMOOTH);
     glEnable(GL_COLOR_MATERIAL);
     glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE);
+    Screenshot::Init();
 
     // set up our 3D camera (see stereohelper.h for more documentation)
     cam.type = StereoHelper::PARALLEL_AXIS_ASYMMETRIC;

src/screenshot.cpp

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <GL/glut.h>
+
+#include "screenshot.h"
+
+void Screenshot::Init() {
+    // byte alignment
+    glPixelStorei(GL_PACK_ALIGNMENT, 1);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+}
+
+void Screenshot::Screenshot(int x, int y, int w, int h, const char *filename) {
+    // read from the front buffer
+    glReadBuffer(GL_FRONT);
+
+    // grab the pixel data
+    uint8_t buffer[w * h * (3 * sizeof(uint8_t))];
+    glReadPixels(x, y, w, h, GL_RGB, GL_UNSIGNED_BYTE, buffer);
+
+    // open the file for writing
+    FILE *fp = fopen(filename, "wb");
+    if (fp == NULL) {
+        perror("Failed to open screenshot file for writing!");
+        exit(EXIT_FAILURE);
+    }
+
+    // write 24-bit uncompressed targa header
+    // thanks to Paul Bourke (http://local.wasp.uwa.edu.au/~pbourke/dataformats/tga/)
+    putc(0, fp);
+    putc(0, fp);
+    putc(2, fp); // type is uncompressed RGB
+    putc(0, fp);
+    putc(0, fp);
+    putc(0, fp);
+    putc(0, fp);
+    putc(0, fp);
+    putc(0, fp); // x origin, low byte
+    putc(0, fp); // x origin, high byte
+    putc(0, fp); // y origin, low byte
+    putc(0, fp); // y origin, high byte
+    putc(w & 0xff, fp); // width, low byte
+    putc((w & 0xff00) >> 8, fp); // width, high byte
+    putc(h & 0xff, fp); // height, low byte
+    putc((h & 0xff00) >> 8, fp); // height, high byte
+    putc(24, fp); // 24-bit color depth
+    putc(0, fp);
+
+    // write the image data
+    for (int j = 0; j < h; j++) {
+        for (int i = 0; i < w; i++) {
+            // calculate the offset into the buffer
+            int offset = (i + j * w) * (3 * sizeof(uint8_t));
+
+            // copy out the bytes
+            uint8_t r = buffer[offset + 0];
+            uint8_t g = buffer[offset + 1];
+            uint8_t b = buffer[offset + 2];
+
+            // write out the bytes in BGR order
+            putc(b, fp);
+            putc(g, fp);
+            putc(r, fp);
+        }
+    }
+
+    fclose(fp);
+}

src/screenshot.h

@@ -0,0 +1,16 @@
+#ifndef __SCREENSHOT_H__
+#define __SCREENSHOT_H__
+
+namespace Screenshot {
+
+    // Sets OpenGL state such that we can take screenshots later.
+    void Init();
+
+    // Writes the framebuffer to a targa file with the specified filename.
+    // Region is from (x, y) in the bottom left to (x + w, y + h) in the top
+    // right.
+    void Screenshot(int x, int y, int w, int h, const char *filename);
+
+}
+
+#endif // __SCREENSHOT_H__