421 lines
10 KiB
C
421 lines
10 KiB
C
/*
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* EXT_fog_coord.
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*
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* Based on glutskel.c by Brian Paul
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* and NeHe's Volumetric fog tutorial!
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*
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* Daniel Borca
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/glut.h>
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#include "readtex.h"
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#define TEXTURE_FILE "../images/bw.rgb"
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#define ARRAYS 0 /* use glDrawElements */
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#define VERBOSE 1 /* tell me what happens */
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#define DEPTH 15.0f
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#if !defined(GLAPIENTRYP)
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# define GLAPIENTRYP *
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#endif
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typedef void (GLAPIENTRYP GLFOGCOORDFEXTPROC) (GLfloat f);
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typedef void (GLAPIENTRYP GLFOGCOORDPOINTEREXTPROC) (GLenum, GLsizei, const GLvoid *);
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static GLFOGCOORDFEXTPROC glFogCoordf_ext;
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#if ARRAYS
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static GLFOGCOORDPOINTEREXTPROC glFogCoordPointer_ext;
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#endif
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static GLboolean have_fog_coord;
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static GLfloat camz;
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static GLuint texture[1];
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static GLint fogMode;
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static GLboolean fogCoord;
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static GLfloat fogDensity = 0.75;
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static GLfloat fogStart = 1.0, fogEnd = 40.0;
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static GLfloat fogColor[4] = {0.6f, 0.3f, 0.0f, 1.0f};
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static void APIENTRY glFogCoordf_nop (GLfloat f)
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{
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(void)f;
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}
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static int BuildTexture (const char *filename, GLuint texid[])
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{
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GLubyte *tex_data;
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GLenum tex_format;
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GLint tex_width, tex_height;
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tex_data = LoadRGBImage(filename, &tex_width, &tex_height, &tex_format);
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if (tex_data == NULL) {
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return -1;
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}
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{
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GLint tex_max;
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glGetIntegerv(GL_MAX_TEXTURE_SIZE, &tex_max);
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if ((tex_width > tex_max) || (tex_height > tex_max)) {
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return -1;
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}
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}
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glGenTextures(1, texid);
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glBindTexture(GL_TEXTURE_2D, texid[0]);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glTexImage2D(GL_TEXTURE_2D, 0, tex_format, tex_width, tex_height, 0,
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tex_format, GL_UNSIGNED_BYTE, tex_data);
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return 0;
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}
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static int SetFogMode (GLint fogMode)
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{
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fogMode &= 3;
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switch (fogMode) {
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case 0:
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glDisable(GL_FOG);
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#if VERBOSE
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printf("fog(disable)\n");
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#endif
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break;
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case 1:
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glEnable(GL_FOG);
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glFogi(GL_FOG_MODE, GL_LINEAR);
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glFogf(GL_FOG_START, fogStart);
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glFogf(GL_FOG_END, fogEnd);
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#if VERBOSE
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printf("fog(GL_LINEAR, %.2f, %.2f)\n", fogStart, fogEnd);
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#endif
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break;
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case 2:
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glEnable(GL_FOG);
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glFogi(GL_FOG_MODE, GL_EXP);
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glFogf(GL_FOG_DENSITY, fogDensity);
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#if VERBOSE
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printf("fog(GL_EXP, %.2f)\n", fogDensity);
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#endif
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break;
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case 3:
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glEnable(GL_FOG);
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glFogi(GL_FOG_MODE, GL_EXP2);
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glFogf(GL_FOG_DENSITY, fogDensity);
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#if VERBOSE
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printf("fog(GL_EXP2, %.2f)\n", fogDensity);
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#endif
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break;
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}
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return fogMode;
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}
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static GLboolean SetFogCoord (GLboolean fogCoord)
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{
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glFogCoordf_ext = glFogCoordf_nop;
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if (!have_fog_coord) {
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#if VERBOSE
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printf("fog(GL_FRAGMENT_DEPTH_EXT)%s\n", fogCoord ? " EXT_fog_coord not available!" : "");
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#endif
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return GL_FALSE;
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}
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if (fogCoord) {
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glFogCoordf_ext = (GLFOGCOORDFEXTPROC)glutGetProcAddress("glFogCoordfEXT");
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glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
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#if VERBOSE
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printf("fog(GL_FOG_COORDINATE_EXT)\n");
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#endif
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} else {
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glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
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#if VERBOSE
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printf("fog(GL_FRAGMENT_DEPTH_EXT)\n");
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#endif
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}
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return fogCoord;
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}
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#if ARRAYS
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/* could reuse vertices */
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static GLuint vertex_index[] = {
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/* Back */
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0, 1, 2, 3,
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/* Floor */
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4, 5, 6, 7,
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/* Roof */
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8, 9, 10, 11,
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/* Right */
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12, 13, 14, 15,
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/* Left */
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16, 17, 18, 19
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};
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static GLfloat vertex_pointer[][3] = {
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/* Back */
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{-2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH}, { 2.5f, 2.5f,-DEPTH}, {-2.5f, 2.5f,-DEPTH},
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/* Floor */
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{-2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH}, { 2.5f,-2.5f, DEPTH}, {-2.5f,-2.5f, DEPTH},
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/* Roof */
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{-2.5f, 2.5f,-DEPTH}, { 2.5f, 2.5f,-DEPTH}, { 2.5f, 2.5f, DEPTH}, {-2.5f, 2.5f, DEPTH},
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/* Right */
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{ 2.5f,-2.5f, DEPTH}, { 2.5f, 2.5f, DEPTH}, { 2.5f, 2.5f,-DEPTH}, { 2.5f,-2.5f,-DEPTH},
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/* Left */
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{-2.5f,-2.5f, DEPTH}, {-2.5f, 2.5f, DEPTH}, {-2.5f, 2.5f,-DEPTH}, {-2.5f,-2.5f,-DEPTH}
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};
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static GLfloat texcoord_pointer[][2] = {
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/* Back */
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{0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
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/* Floor */
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{0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
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/* Roof */
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{0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
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/* Right */
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{0.0f, 0.0f}, {0.0f, 1.0f}, {1.0f, 1.0f}, {1.0f, 0.0f},
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/* Left */
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{0.0f, 0.0f}, {0.0f, 1.0f}, {1.0f, 1.0f}, {1.0f, 0.0f}
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};
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static GLfloat fogcoord_pointer[][1] = {
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/* Back */
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{1.0f}, {1.0f}, {1.0f}, {1.0f},
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/* Floor */
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{1.0f}, {1.0f}, {0.0f}, {0.0f},
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/* Roof */
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{1.0f}, {1.0f}, {0.0f}, {0.0f},
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/* Right */
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{0.0f}, {0.0f}, {1.0f}, {1.0f},
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/* Left */
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{0.0f}, {0.0f}, {1.0f}, {1.0f}
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};
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#endif
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static void Display( void )
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{
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glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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glLoadIdentity ();
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glTranslatef(0.0f, 0.0f, camz);
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#if ARRAYS
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glDrawElements(GL_QUADS, sizeof(vertex_index) / sizeof(vertex_index[0]), GL_UNSIGNED_INT, vertex_index);
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#else
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/* Back */
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glBegin(GL_QUADS);
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glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
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glEnd();
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/* Floor */
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glBegin(GL_QUADS);
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glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f,-2.5f, DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f,-2.5f, DEPTH);
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glEnd();
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/* Roof */
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glBegin(GL_QUADS);
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glFogCoordf_ext(1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f, DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f, DEPTH);
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glEnd();
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/* Right */
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glBegin(GL_QUADS);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 2.5f,-2.5f, DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 2.5f, 2.5f, DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 2.5f, 2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 2.5f,-2.5f,-DEPTH);
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glEnd();
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/* Left */
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glBegin(GL_QUADS);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.5f,-2.5f, DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.5f, 2.5f, DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f(-2.5f, 2.5f,-DEPTH);
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glFogCoordf_ext(1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f(-2.5f,-2.5f,-DEPTH);
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glEnd();
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#endif
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glutSwapBuffers();
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}
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static void Reshape( int width, int height )
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{
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluPerspective(45.0f, (GLfloat)(width)/(GLfloat)(height), 0.1f, 100.0f);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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}
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static void Key( unsigned char key, int x, int y )
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{
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(void) x;
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(void) y;
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switch (key) {
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case 'f':
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fogMode = SetFogMode(fogMode + 1);
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break;
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case '+':
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if (fogDensity < 1.0) {
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fogDensity += 0.05;
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}
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SetFogMode(fogMode);
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break;
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case '-':
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if (fogDensity > 0.0) {
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fogDensity -= 0.05;
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}
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SetFogMode(fogMode);
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break;
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case 's':
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if (fogStart > 0.0) {
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fogStart -= 1.0;
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}
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SetFogMode(fogMode);
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break;
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case 'S':
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if (fogStart < fogEnd) {
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fogStart += 1.0;
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}
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SetFogMode(fogMode);
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break;
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case 'e':
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if (fogEnd > fogStart) {
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fogEnd -= 1.0;
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}
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SetFogMode(fogMode);
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break;
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case 'E':
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if (fogEnd < 100.0) {
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fogEnd += 1.0;
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}
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SetFogMode(fogMode);
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break;
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case 'c':
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fogCoord = SetFogCoord(fogCoord ^ GL_TRUE);
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break;
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case 27:
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void SpecialKey( int key, int x, int y )
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{
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(void) x;
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(void) y;
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switch (key) {
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case GLUT_KEY_UP:
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if (camz < (DEPTH - 1.0)) {
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camz += 1.0f;
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}
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break;
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case GLUT_KEY_DOWN:
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if (camz > -19.0) {
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camz -= 1.0f;
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}
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break;
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}
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glutPostRedisplay();
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}
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static void Init( void )
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{
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have_fog_coord = glutExtensionSupported("GL_EXT_fog_coord");
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if (BuildTexture(TEXTURE_FILE, texture) == -1) {
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exit(1);
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}
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glEnable(GL_TEXTURE_2D);
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glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
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glClearDepth(1.0f);
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glDepthFunc(GL_LEQUAL);
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glEnable(GL_DEPTH_TEST);
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glShadeModel(GL_SMOOTH);
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glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
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glFogfv(GL_FOG_COLOR, fogColor);
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glHint(GL_FOG_HINT, GL_NICEST);
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fogCoord = SetFogCoord(GL_TRUE); /* try to enable fog_coord */
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fogMode = SetFogMode(2); /* GL_EXP */
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camz = -19.0f;
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#if ARRAYS
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glEnableClientState(GL_VERTEX_ARRAY);
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glVertexPointer(3, GL_FLOAT, 0, vertex_pointer);
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glTexCoordPointer(2, GL_FLOAT, 0, texcoord_pointer);
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if (have_fog_coord) {
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glFogCoordPointer_ext = (GLFOGCOORDPOINTEREXTPROC)glutGetProcAddress("glFogCoordPointerEXT");
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glEnableClientState(GL_FOG_COORDINATE_ARRAY_EXT);
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glFogCoordPointer_ext(GL_FLOAT, 0, fogcoord_pointer);
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}
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#endif
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}
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int main( int argc, char *argv[] )
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{
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glutInit( &argc, argv );
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glutInitWindowPosition( 0, 0 );
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glutInitWindowSize( 640, 480 );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
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glutCreateWindow(argv[0]);
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glutReshapeFunc( Reshape );
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glutKeyboardFunc( Key );
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glutSpecialFunc( SpecialKey );
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glutDisplayFunc( Display );
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Init();
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glutMainLoop();
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return 0;
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}
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