--- /dev/null
+/* thunder. c */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <assert.h>
+#include "imago2.h"
+#include "demo.h"
+#include "screen.h"
+
+/* Render blur in half x half dimenstions. Add one pixel padding in all
+ * directions (2 pixels horizontally, 2 pixels vertically).
+ */
+#define BLUR_BUFFER_WIDTH (320/2 + 2)
+#define BLUR_BUFFER_HEIGHT (240/2 + 2)
+#define BLUR_BUFFER_SIZE (BLUR_BUFFER_WIDTH * BLUR_BUFFER_HEIGHT)
+static unsigned char *blurBuffer, *blurBuffer2;
+
+/* TODO: Load palette from file */
+static unsigned short palette[256];
+
+void clearBlurBuffer();
+void drawPatternOnBlurBuffer();
+void applyBlur();
+void blitEffect();
+
+static int init(void);
+static void destroy(void);
+static void start(long trans_time);
+static void stop(long trans_time);
+static void draw(void);
+
+static unsigned int lastFrameTime = 0;
+static float lastFrameDuration = 0.0f;
+static struct screen scr = {
+ "thunder",
+ init,
+ destroy,
+ start,
+ 0,
+ draw
+};
+
+struct screen *thunder_screen(void)
+{
+ return &scr;
+}
+
+static int init(void)
+{
+ int i = 0;
+
+ blurBuffer = malloc(BLUR_BUFFER_SIZE);
+ blurBuffer2 = malloc(BLUR_BUFFER_SIZE);
+
+ clearBlurBuffer();
+
+ /* For now, map to blue */
+ for (i = 0; i < 256; i++) {
+ palette[i] = i >> 3;
+ }
+
+ return 0;
+}
+
+static void destroy(void)
+{
+ free(blurBuffer);
+ blurBuffer = 0;
+
+ free(blurBuffer2);
+ blurBuffer2 = 0;
+}
+
+static void start(long trans_time)
+{
+ lastFrameTime = time_msec;
+}
+
+
+static void draw(void)
+{
+
+ lastFrameDuration = (time_msec - lastFrameTime) / 1000.0f;
+ lastFrameTime = time_msec;
+
+ drawPatternOnBlurBuffer();
+ applyBlur();
+ blitEffect();
+
+ swap_buffers(0);
+}
+
+void clearBlurBuffer() {
+ /* Clear the whole buffer (including its padding ) */
+ memset(blurBuffer, 0, BLUR_BUFFER_SIZE);
+ memset(blurBuffer2, 0, BLUR_BUFFER_SIZE);
+}
+
+void drawPatternOnBlurBuffer() {
+ int i, j;
+ unsigned char *dst = blurBuffer + BLUR_BUFFER_WIDTH + 1;
+ int starty, stopy, startx, stopx;
+
+ starty = rand() % 60;
+ stopy = starty + rand() % 60;
+ startx = rand() % 80;
+ stopx = startx + rand() % 80;
+
+ if (rand() % 2) return;
+
+ for (j = starty; j < stopy; j++) {
+ for (i = startx; i < stopx; i++) {
+ dst[i + j * BLUR_BUFFER_WIDTH] = 255;
+ }
+ }
+}
+
+void applyBlur() {
+ int i, j;
+ unsigned char *tmp;
+ unsigned char *src = blurBuffer + BLUR_BUFFER_WIDTH + 1;
+ unsigned char *dst = blurBuffer2 + BLUR_BUFFER_WIDTH + 1;
+
+ for (j = 0; j < 120; j++) {
+ for (i = 0; i < 160; i++) {
+ *dst = (*(src - 1) + *(src + 1) + *(src - BLUR_BUFFER_WIDTH) + *(src + BLUR_BUFFER_WIDTH)) >> 2;
+ dst++;
+ src++;
+ }
+ /* Just skip the padding since we went through the scanline in the inner loop (except from the padding) */
+ src += 2;
+ dst += 2;
+ }
+
+ /* Swap blur buffers */
+ tmp = blurBuffer;
+ blurBuffer = blurBuffer2;
+ blurBuffer2 = tmp;
+}
+
+void blitEffect() {
+ unsigned int *dst1 = (unsigned int*) vmem_back;
+ unsigned int *dst2 = dst1 + 160; /* We're writing two pixels at once */
+ unsigned char *src1 = blurBuffer + BLUR_BUFFER_WIDTH + 1;
+ unsigned char *src2 = src1 + BLUR_BUFFER_WIDTH;
+ unsigned char tl, tr, bl, br;
+ int i, j;
+
+ for (j = 0; j < 120; j++) {
+ for (i = 0; i < 160; i++) {
+ tl = *src1;
+ tr = (*src1 + *(src1 + 1)) >> 1;
+ bl = (*src1 + *src2) >> 1;
+ br = tr + ((*src2 + *(src2 + 1)) >> 1) >> 1;
+
+ /* Pack 2 pixels in each 32 bit word */
+ *dst1 = (palette[tr] << 16) | palette[tl];
+ *dst2 = (palette[br] << 16) | palette[bl];
+
+ dst1++;
+ src1++;
+ dst2++;
+ src2++;
+ }
+ /* Again, skip padding */
+ src1 += 2;
+ src2 += 2;
+
+ /* For now, skip a scanline */
+ dst1 += 160;
+ dst2 += 160;
+ }
+
+}
+
+
+
+
+