void init(void)
{
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glClearColor(0.0, 0.0, 0.0, 0.0);
glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, GL_FALSE);
glEnable(GL_HISTOGRAM);
}
void init(void) {
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
makeCheckImage();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glHistogram(GL_HISTOGRAM, histogram_size, GL_RGB, GL_FALSE);
glEnable(GL_HISTOGRAM);
}
void __glXDisp_Histogram(GLbyte *pc)
{
glHistogram(
*(GLenum *)(pc + 0),
*(GLsizei *)(pc + 4),
*(GLenum *)(pc + 8),
*(GLboolean *)(pc + 12)
);
}
void keyboard(unsigned char key, int x, int y)
{
static GLboolean sink = GL_FALSE;
switch (key) {
case 's' :
sink = !sink;
glHistogram(GL_HISTOGRAM, HISTOGRAM_SIZE, GL_RGB, sink);
break;
case 27:
exit(0);
}
glutPostRedisplay();
}
JNIEXPORT void JNICALL Java_org_lwjgl_opengl_ARBImaging_nglHistogram(JNIEnv *env, jclass clazz, jint target, jint width, jint internalformat, jboolean sink, jlong function_pointer) {
glHistogramPROC glHistogram = (glHistogramPROC)((intptr_t)function_pointer);
glHistogram(target, width, internalformat, sink);
}
/**
* If enabled, histogram incoming RGBA color values.
* See https://www.opengl.org/sdk/docs/man3/xhtml/glHistogram.xml
*/
void rendering::ReadHistogramParameter()
{
if (supportedOpenGLLevel > 300)
{
INFO_LOG_RENDERING("Histogram not supported in OpenGL version higher than 3.0");
CheckErrorCode(__FUNCTION__, "Initializing histogram parameters");
return;
}
const auto histogramEnabled = GET_CONFIG_VALUE_RENDERING("GL_HISTOGRAM_ENABLED", 0);
if (histogramEnabled == 0)
{
glDisable(GL_HISTOGRAM);
DEBUG_LOG_RENDERING("GL_HISTOGRAM disabled");
CheckErrorCode(__FUNCTION__, "Initializing histogram parameters");
return;
}
glEnable(GL_HISTOGRAM);
auto histogramTargetStr = GET_CONFIG_VALUE_STR_RENDERING("GL_HISTOGRAM_TARGET", "GL_HISTOGRAM");
GLenum histogramTarget;
if (histogramTargetStr == "GL_HISTOGRAM") { histogramTarget = GL_HISTOGRAM; }
else if (histogramTargetStr == "GL_PROXY_HISTOGRAM") { histogramTarget = GL_PROXY_HISTOGRAM; }
else /* GL_HISTOGRAM is default */
{
ERROR_LOG_RENDERING("Invalid enum \"", histogramTargetStr, "\" given for the histogram target parameter. Using default GL_HISTOGRAM");
histogramTargetStr = "GL_HISTOGRAM";
histogramTarget = GL_HISTOGRAM;
}
const auto histogramWidth = GET_CONFIG_VALUE_RENDERING("GL_HISTOGRAM_WIDTH", 16); // must be a power of 2
auto histogramInternalFormatStr = GET_CONFIG_VALUE_STR_RENDERING("GL_HISTOGRAM_INTERNAL_FORMAT", "GL_ALPHA");
GLenum histogramInternalFormat;
if (histogramInternalFormatStr == "GL_ALPHA") { histogramInternalFormat = GL_ALPHA; }
else if (histogramInternalFormatStr == "GL_ALPHA4") { histogramInternalFormat = GL_ALPHA4; }
else if (histogramInternalFormatStr == "GL_ALPHA8") { histogramInternalFormat = GL_ALPHA8; }
else if (histogramInternalFormatStr == "GL_ALPHA12") { histogramInternalFormat = GL_ALPHA12; }
else if (histogramInternalFormatStr == "GL_ALPHA16") { histogramInternalFormat = GL_ALPHA16; }
else if (histogramInternalFormatStr == "GL_LUMINANCE") { histogramInternalFormat = GL_LUMINANCE; }
else if (histogramInternalFormatStr == "GL_LUMINANCE4") { histogramInternalFormat = GL_LUMINANCE4; }
else if (histogramInternalFormatStr == "GL_LUMINANCE8") { histogramInternalFormat = GL_LUMINANCE8; }
else if (histogramInternalFormatStr == "GL_LUMINANCE12") { histogramInternalFormat = GL_LUMINANCE12; }
else if (histogramInternalFormatStr == "GL_LUMINANCE16") { histogramInternalFormat = GL_LUMINANCE16; }
else if (histogramInternalFormatStr == "GL_LUMINANCE_ALPHA") { histogramInternalFormat = GL_LUMINANCE_ALPHA; }
else if (histogramInternalFormatStr == "GL_LUMINANCE4_ALPHA4") { histogramInternalFormat = GL_LUMINANCE4_ALPHA4; }
else if (histogramInternalFormatStr == "GL_LUMINANCE6_ALPHA2") { histogramInternalFormat = GL_LUMINANCE6_ALPHA2; }
else if (histogramInternalFormatStr == "GL_LUMINANCE8_ALPHA8") { histogramInternalFormat = GL_LUMINANCE8_ALPHA8; }
else if (histogramInternalFormatStr == "GL_LUMINANCE12_ALPHA4") { histogramInternalFormat = GL_LUMINANCE12_ALPHA4; }
else if (histogramInternalFormatStr == "GL_LUMINANCE12_ALPHA12") { histogramInternalFormat = GL_LUMINANCE12_ALPHA12; }
else if (histogramInternalFormatStr == "GL_LUMINANCE16_ALPHA16") { histogramInternalFormat = GL_LUMINANCE16_ALPHA16; }
else if (histogramInternalFormatStr == "GL_R3_G3_B2") { histogramInternalFormat = GL_R3_G3_B2; }
else if (histogramInternalFormatStr == "GL_RGB") { histogramInternalFormat = GL_RGB; }
else if (histogramInternalFormatStr == "GL_RGB4") { histogramInternalFormat = GL_RGB4; }
else if (histogramInternalFormatStr == "GL_RGB5") { histogramInternalFormat = GL_RGB5; }
else if (histogramInternalFormatStr == "GL_RGB8") { histogramInternalFormat = GL_RGB8; }
else if (histogramInternalFormatStr == "GL_RGB10") { histogramInternalFormat = GL_RGB10; }
else if (histogramInternalFormatStr == "GL_RGB12") { histogramInternalFormat = GL_RGB12; }
else if (histogramInternalFormatStr == "GL_RGB16") { histogramInternalFormat = GL_RGB16; }
else if (histogramInternalFormatStr == "GL_RGBA") { histogramInternalFormat = GL_RGBA; }
else if (histogramInternalFormatStr == "GL_RGBA2") { histogramInternalFormat = GL_RGBA2; }
else if (histogramInternalFormatStr == "GL_RGBA4") { histogramInternalFormat = GL_RGBA4; }
else if (histogramInternalFormatStr == "GL_RGB5_A1") { histogramInternalFormat = GL_RGB5_A1; }
else if (histogramInternalFormatStr == "GL_RGBA8") { histogramInternalFormat = GL_RGBA8; }
else if (histogramInternalFormatStr == "GL_RGB10_A2") { histogramInternalFormat = GL_RGB10_A2; }
else if (histogramInternalFormatStr == "GL_RGBA12") { histogramInternalFormat = GL_RGBA12; }
else if (histogramInternalFormatStr == "GL_RGBA16") { histogramInternalFormat = GL_RGBA16; }
else /* GL_RGBA is default */
{
ERROR_LOG_RENDERING("Invalid enum \"", histogramInternalFormatStr, "\" given for the histogram internal format. Using default GL_RGBA");
histogramInternalFormatStr = "GL_RGBA";
histogramInternalFormat = GL_RGBA;
}
const auto histogramSink = GET_CONFIG_VALUE_RENDERING("GL_HISTOGRAM_SINK", false);
glHistogram(histogramTarget, histogramWidth, histogramInternalFormat, histogramSink);
if (histogramSink)
{
INFO_LOG_RENDERING("GL_HISTOGRAM enabled with target = \"", histogramTargetStr, "\", width = ", histogramWidth, ", internal format = \"", histogramInternalFormatStr, "\" and enabled sink");
}
else
{
INFO_LOG_RENDERING("GL_HISTOGRAM enabled with target = \"", histogramTargetStr, "\", width = ", histogramWidth, ", internal format = \"", histogramInternalFormatStr, "\" and disabled sink");
}
CheckErrorCode(__FUNCTION__, "Initializing histogram parameters");
}
///////////////////////////////////////////////////////////////////////
// Called to draw scene
void RenderScene(void)
{
GLint i; // Looping variable
GLint iViewport[4]; // Viewport
GLint iLargest; // Largest histogram value
static GLubyte invertTable[256][3];// Inverted color table
// Do a black and white scaling
static GLfloat lumMat[16] = { 0.30f, 0.30f, 0.30f, 0.0f,
0.59f, 0.59f, 0.59f, 0.0f,
0.11f, 0.11f, 0.11f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f };
static GLfloat mSharpen[3][3] = { // Sharpen convolution kernel
{0.0f, -1.0f, 0.0f},
{-1.0f, 5.0f, -1.0f },
{0.0f, -1.0f, 0.0f }};
static GLfloat mEmboss[3][3] = { // Emboss convolution kernel
{ 2.0f, 0.0f, 0.0f },
{ 0.0f, -1.0f, 0.0f },
{ 0.0f, 0.0f, -1.0f }};
static GLint histoGram[256]; // Storeage for histogram statistics
// Clear the window with current clearing color
glClear(GL_COLOR_BUFFER_BIT);
// Current Raster Position always at bottom left hand corner of window
glRasterPos2i(0, 0);
glGetIntegerv(GL_VIEWPORT, iViewport);
glPixelZoom((GLfloat) iViewport[2] / (GLfloat)iWidth, (GLfloat) iViewport[3] / (GLfloat)iHeight);
if(bHistogram == GL_TRUE) // Collect Historgram data
{
// We are collecting luminance data, use our conversion formula
// instead of OpenGL's (which just adds color components together)
glMatrixMode(GL_COLOR);
glLoadMatrixf(lumMat);
glMatrixMode(GL_MODELVIEW);
// Start collecting histogram data, 256 luminance values
glHistogram(GL_HISTOGRAM, 256, GL_LUMINANCE, GL_FALSE);
glEnable(GL_HISTOGRAM);
}
// Do image operation, depending on rendermode index
switch(iRenderMode)
{
case 5: // Sharpen image
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_RGB, 3, 3, GL_LUMINANCE, GL_FLOAT, mSharpen);
glEnable(GL_CONVOLUTION_2D);
break;
case 4: // Emboss image
glConvolutionFilter2D(GL_CONVOLUTION_2D, GL_RGB, 3, 3, GL_LUMINANCE, GL_FLOAT, mEmboss);
glEnable(GL_CONVOLUTION_2D);
glMatrixMode(GL_COLOR);
glLoadMatrixf(lumMat);
glMatrixMode(GL_MODELVIEW);
break;
case 3: // Invert Image
for(i = 0; i < 255; i++)
{
invertTable[i][0] = (GLubyte)(255 - i);
invertTable[i][1] = (GLubyte)(255 - i);
invertTable[i][2] = (GLubyte)(255 - i);
}
glColorTable(GL_COLOR_TABLE, GL_RGB, 256, GL_RGB, GL_UNSIGNED_BYTE, invertTable);
glEnable(GL_COLOR_TABLE);
break;
case 2: // Brighten Image
glMatrixMode(GL_COLOR);
glScalef(1.25f, 1.25f, 1.25f);
glMatrixMode(GL_MODELVIEW);
break;
case 1: // Just do a plain old image copy
default:
// This line intentially left blank
break;
}
// Do the pixel draw
glDrawPixels(iWidth, iHeight, eFormat, GL_UNSIGNED_BYTE, pImage);
// Fetch and draw histogram?
if(bHistogram == GL_TRUE)
{
// Read histogram data into buffer
glGetHistogram(GL_HISTOGRAM, GL_TRUE, GL_LUMINANCE, GL_INT, histoGram);
// Find largest value for scaling graph down
iLargest = 0;
for(i = 0; i < 255; i++)
if(iLargest < histoGram[i])
iLargest = histoGram[i];
// White lines
glColor3f(1.0f, 1.0f, 1.0f);
glBegin(GL_LINE_STRIP);
for(i = 0; i < 255; i++)
glVertex2f((GLfloat)i, (GLfloat)histoGram[i] / (GLfloat) iLargest * 128.0f);
glEnd();
bHistogram = GL_FALSE;
glDisable(GL_HISTOGRAM);
}
// Reset everyting to default
glMatrixMode(GL_COLOR);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glDisable(GL_CONVOLUTION_2D);
glDisable(GL_COLOR_TABLE);
// Show our hard work...
glutSwapBuffers();
}
