Rain.cpp File Reference

Rain project source code. More...

#include <particle/papi.h>
#include <GL/glut.h>
#include <im.h>
#include <im_image.h>
#include <im_convert.h>

Functions
void	MakeRainStreaksTexture ()
	makes the rain streaks texture for testing
void	LoadBackgroundImage (char *file_name)
	loads the image for the background
void	ComputeParticles ()
	calculates the particle dynamics
void	DrawGroupAsPoints ()
	renders the points
void	drawParticles ()
	renders the particles
void	drawBackground ()
void	Draw ()
	OpenGL registrered rendering method.
void	Reshape (int w, int h)
void	initGL ()
int	main (int argc, char **argv)
Variables
imImage *	bg_image = NULL
imImage *	tex_image = NULL
unsigned char *	gl_bg_data = NULL
unsigned char *	gl_tex_data_R = NULL
unsigned char *	gl_tex_data_G = NULL
unsigned char *	gl_tex_data_B = NULL
unsigned char *	gl_tex_data_RGBA = NULL
GLuint	tex_id = -1
GLuint	SpotTexID = -1

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Detailed Description

Rain project source code.

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Function Documentation

ComputeParticles (   )

calculates the particle dynamics The control over the Particles API is done here { // Set up the state. pVelocityD(PDLine(pVec(0.0,0.0,0.1),pVec(0.0,0.0,0.0))); pColorD(PDLine(pVec(0.8, 0.9, 1.0), pVec(0.1, 1.0, 1.0))); pSize(1.5); pStartingAge(0); // Generate particles along a very small line in the nozzle. //pSource(2, PDLine(pVec(0.0, 0.0, 0.0), pVec(0.0, 0.0, 0.405))); pSource(200,PDBox(pVec(-3.5,-3.5,0.0),pVec(3.5,3.5,0.5))); // Gravity. pGravity(pVec(0.0, 0.0, -0.01)); // Kill particles below Z=-3. pSink(false, PDPlane(pVec(0,0,0), pVec(0,0,1))); // Move particles to their new positions. pMove(); }

Draw (   )

OpenGL registrered rendering method. The rendering consists of : 1- clean up the buffers 2- drawing the background on the back color buffer 3- drawing the particles on the back color buffer 4- blitting { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_PROJECTION); // Draws the background drawBackground(); // Do what the particles do. ComputeParticles(); // Draw the particles. drawParticles(); // shows everything... glutSwapBuffers(); }

DrawGroupAsPoints (   )

renders the points We have used the Array implementation for performance to draw as textured point sprites just call glEnable(GL_POINT_SPRITE_ARB) before calling this function and after binding the texture. { int cnt = (int)pGetGroupCount(); if(cnt < 1) return; float *ptr; size_t flstride, pos3Ofs, posB3Ofs, size3Ofs, vel3Ofs, velB3Ofs, color3Ofs, alpha1Ofs, age1Ofs; cnt = (int)pGetParticlePointer(ptr, flstride, pos3Ofs, posB3Ofs, size3Ofs, vel3Ofs, velB3Ofs, color3Ofs, alpha1Ofs, age1Ofs); if(cnt < 1) return; glEnableClientState(GL_COLOR_ARRAY); glColorPointer(4, GL_FLOAT, int(flstride) * sizeof(float), ptr + color3Ofs); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, int(flstride) * sizeof(float), ptr + pos3Ofs); glDrawArrays(GL_POINTS, 0, cnt); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_COLOR_ARRAY); }

drawParticles (   )

renders the particles We have used Perspective projection for this... TODO { glLoadIdentity(); gluPerspective(10, bg_image->width / double(bg_image->height), 1, 100); gluLookAt(0, -8, 3, 0, 0, 0, 0, 0, 1); DrawGroupAsPoints(); }

LoadBackgroundImage (  char *  file_name  )

loads the image for the background The IM package will take are of most common formats... { int error; bg_image = imFileImageLoadBitmap(file_name, 0, &error); gl_bg_data = (unsigned char*) malloc(bg_image->size); imConvertPacking(bg_image->data[0], gl_bg_data, bg_image->width, bg_image->height, bg_image->depth, bg_image->data_type, 0); }

MakeRainStreaksTexture (   )

makes the rain streaks texture for testing For OpenGL the texture image must be of the form 2^x { int error; tex_image = imFileImageLoadBitmap("rain_32x32.png", 0, &error); int width = tex_image->width; int height = tex_image->height; gl_tex_data_RGBA = (unsigned char*) malloc(4*width*height); gl_tex_data_R = (unsigned char*) malloc(tex_image->size); gl_tex_data_G = (unsigned char*) malloc(tex_image->size); gl_tex_data_B = (unsigned char*) malloc(tex_image->size); imConvertPacking(tex_image->data[0], gl_tex_data_R, tex_image->width, tex_image->height, tex_image->depth,tex_image->data_type, 0); imConvertPacking(tex_image->data[1], gl_tex_data_G, tex_image->width, tex_image->height, tex_image->depth,tex_image->data_type, 0); imConvertPacking(tex_image->data[2], gl_tex_data_B, tex_image->width, tex_image->height, tex_image->depth,tex_image->data_type, 0); int rgba_count = 0; for(int i=0; i<width; i++) for(int j=0; j<height; j++) { int ch_count = i*width + j; gl_tex_data_RGBA[rgba_count++] = gl_tex_data_R[ch_count]; gl_tex_data_RGBA[rgba_count++] = gl_tex_data_G[ch_count]; gl_tex_data_RGBA[rgba_count++] = gl_tex_data_B[ch_count]; if ((gl_tex_data_R[ch_count] == 0) && (gl_tex_data_G[ch_count] == 0) && (gl_tex_data_B[ch_count] == 0)) gl_tex_data_RGBA[rgba_count++] = 0; else gl_tex_data_RGBA[rgba_count++] = 255; } glGenTextures(1, &tex_id); glBindTexture(GL_TEXTURE_2D, tex_id); glTexImage2D(GL_TEXTURE_2D, 0, 4, tex_image->width, tex_image->height, 0, GL_RGBA, GL_UNSIGNED_BYTE, gl_tex_data_RGBA); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); }

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