427 lines
10 KiB
C
427 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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#define GL_GLEXT_PROTOTYPES
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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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#define DEPTH 5.0f
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static PFNGLFOGCOORDFEXTPROC glFogCoordf_ext;
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static PFNGLFOGCOORDPOINTEREXTPROC glFogCoordPointer_ext;
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static GLboolean have_fog_coord;
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static GLfloat camz;
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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 = DEPTH;
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static GLfloat fogColor[4] = {0.6f, 0.3f, 0.0f, 1.0f};
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static const char *ModeStr = NULL;
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static GLboolean Arrays = GL_FALSE;
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static GLboolean Texture = GL_TRUE;
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static void
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Reset(void)
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{
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fogMode = 1;
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fogCoord = 1;
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fogDensity = 0.75;
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fogStart = 1.0;
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fogEnd = DEPTH;
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Arrays = GL_FALSE;
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Texture = GL_TRUE;
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}
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static void APIENTRY
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glFogCoordf_nop (GLfloat f)
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{
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(void)f;
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}
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static void
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PrintString(const char *s)
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{
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while (*s) {
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glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
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s++;
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}
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}
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static void
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PrintInfo(void)
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{
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char s[100];
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glDisable(GL_FOG);
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glColor3f(0, 1, 1);
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sprintf(s, "Mode(m): %s Start(s/S): %g End(e/E): %g Density(d/D): %g",
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ModeStr, fogStart, fogEnd, fogDensity);
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glWindowPos2iARB(5, 20);
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PrintString(s);
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sprintf(s, "Arrays(a): %s glFogCoord(c): %s EyeZ(z/z): %g",
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(Arrays ? "Yes" : "No"),
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(fogCoord ? "Yes" : "No"),
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camz);
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glWindowPos2iARB(5, 5);
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PrintString(s);
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}
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static int
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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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ModeStr = "Off";
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glDisable(GL_FOG);
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break;
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case 1:
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ModeStr = "GL_LINEAR";
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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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break;
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case 2:
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ModeStr = "GL_EXP";
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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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break;
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case 3:
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ModeStr = "GL_EXP2";
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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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break;
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}
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return fogMode;
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}
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static GLboolean
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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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return GL_FALSE;
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}
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if (fogCoord) {
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glFogCoordf_ext = (PFNGLFOGCOORDFEXTPROC)glutGetProcAddress("glFogCoordfEXT");
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glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
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}
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else {
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glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
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}
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return fogCoord;
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}
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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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{-1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH}, { 1.0f, 1.0f,-DEPTH}, {-1.0f, 1.0f,-DEPTH},
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/* Floor */
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{-1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f, 0.0}, {-1.0f,-1.0f, 0.0},
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/* Roof */
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{-1.0f, 1.0f,-DEPTH}, { 1.0f, 1.0f,-DEPTH}, { 1.0f, 1.0f, 0.0}, {-1.0f, 1.0f, 0.0},
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/* Right */
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{ 1.0f,-1.0f, 0.0}, { 1.0f, 1.0f, 0.0}, { 1.0f, 1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH},
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/* Left */
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{-1.0f,-1.0f, 0.0}, {-1.0f, 1.0f, 0.0}, {-1.0f, 1.0f,-DEPTH}, {-1.0f,-1.0f,-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, DEPTH}, {0.0f, DEPTH},
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/* Roof */
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{1.0f, 0.0f}, {0.0f, 0.0f}, {0.0f, DEPTH}, {1.0f, DEPTH},
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/* Right */
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{0.0f, 1.0f}, {0.0f, 0.0f}, {DEPTH, 0.0f}, {DEPTH, 1.0f},
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/* Left */
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{0.0f, 0.0f}, {0.0f, 1.0f}, {DEPTH, 1.0f}, {DEPTH, 0.0f}
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};
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static GLfloat fogcoord_pointer[] = {
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/* Back */
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DEPTH, DEPTH, DEPTH, DEPTH,
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/* Floor */
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DEPTH, DEPTH, 0.0, 0.0,
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/* Roof */
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DEPTH, DEPTH, 0.0, 0.0,
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/* Right */
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0.0, 0.0, DEPTH, DEPTH,
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/* Left */
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0.0, 0.0, DEPTH, DEPTH
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};
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static void
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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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SetFogMode(fogMode);
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glColor3f(1, 1, 1);
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if (Texture)
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glEnable(GL_TEXTURE_2D);
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if (Arrays) {
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glDrawElements(GL_QUADS, sizeof(vertex_index) / sizeof(vertex_index[0]),
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GL_UNSIGNED_INT, vertex_index);
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glDisableClientState(GL_VERTEX_ARRAY);
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glDisableClientState(GL_TEXTURE_COORD_ARRAY);
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}
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else {
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/* Back */
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glBegin(GL_QUADS);
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glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
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glEnd();
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/* Floor */
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glBegin(GL_QUADS);
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glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f,-DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, DEPTH); glVertex3f( 1.0f,-1.0f,0.0);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, DEPTH); glVertex3f(-1.0f,-1.0f,0.0);
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glEnd();
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/* Roof */
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glBegin(GL_QUADS);
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glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, DEPTH); glVertex3f( 1.0f, 1.0f,0.0);
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glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, DEPTH); glVertex3f(-1.0f, 1.0f,0.0);
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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, 1.0f); glVertex3f( 1.0f,-1.0f,0.0);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, 1.0f,0.0);
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glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 0.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 1.0f); glVertex3f( 1.0f,-1.0f,-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(-1.0f,-1.0f,0.0);
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glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f,0.0);
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glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 1.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
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glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
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glEnd();
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}
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glDisable(GL_TEXTURE_2D);
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PrintInfo();
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glutSwapBuffers();
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}
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static void
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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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glFrustum(-1, 1, -1, 1, 1.0, 100);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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}
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static void
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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 'a':
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Arrays = !Arrays;
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break;
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case 'f':
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case 'm':
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fogMode = SetFogMode(fogMode + 1);
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break;
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case 'D':
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fogDensity += 0.05;
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SetFogMode(fogMode);
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break;
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case 'd':
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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 -= 0.25;
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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 < 100.0) {
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fogStart += 0.25;
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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 > 0.0) {
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fogEnd -= 0.25;
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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 += 0.25;
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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 't':
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Texture = !Texture;
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break;
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case 'z':
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camz -= 0.1;
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break;
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case 'Z':
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camz += 0.1;
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break;
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case 'r':
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Reset();
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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
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Init(void)
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{
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static const GLubyte teximage[2][2][4] = {
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{ { 255, 255, 255, 255}, { 128, 128, 128, 255} },
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{ { 128, 128, 128, 255}, { 255, 255, 255, 255} }
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};
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printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
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have_fog_coord = glutExtensionSupported("GL_EXT_fog_coord");
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if (!have_fog_coord) {
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printf("GL_EXT_fog_coord not supported!\n");
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}
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0,
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GL_RGBA, GL_UNSIGNED_BYTE, teximage);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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glClearColor(0.1f, 0.1f, 0.1f, 0.0f);
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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(1);
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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 = (PFNGLFOGCOORDPOINTEREXTPROC)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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Reset();
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}
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int
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main( int argc, char *argv[] )
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{
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glutInit( &argc, argv );
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glutInitWindowSize( 600, 600 );
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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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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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