text.cpp

游戏编程精粹2第六章源码

/* Copyright (C) Dante Treglia II, 2000. 
 * All rights reserved worldwide.
 *
 * This software is provided "as is" without express or implied
 * warranties. You may freely copy and compile this source into
 * applications you distribute provided that the copyright text
 * below is included in the resulting source code, for example:
 * "Portions Copyright (C) Dante Treglia II, 2000"
 */
#ifdef _WIN32
#include <windows.h>
#endif
#include <GL/gl.h>
#include <malloc.h>
#ifndef _WIN32
#include <string.h>
#include <assert.h>
#endif
#include "text.h"

//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// The text texture only needs to be initialized once
static unsigned int fontID = 0;
// Forward definition
extern unsigned char fontData[];

#define FONT_W 8
#define FONT_H 8
#define FONT_DRAW_W 8
#define FONT_DRAW_H 9
#define FONT_TEX_W 64
#define FONT_TEX_H 128

//---------------------------------------------------------------------------
// A text box constructor
//---------------------------------------------------------------------------
TextBox::TextBox(int inL, int inR, int inT, int inB) {
	// Calculate the Text box boundaries
	boxL = inL;
	boxR = inL + ((inR - inL) - ((inR - inL) % FONT_DRAW_W));
	boxT = inT;
	boxB = inT + ((inB - inT) - ((inB - inT) % FONT_DRAW_H));
	// Initialize the Buffers and Pointers
	buffer = (char *)malloc(MAX_STR);
	buffer[0] = '\0';
	drawBufferPtr = buffer;
	// Calculate the number of lines per Page
	pageLineCnt = (boxB - boxT) / FONT_DRAW_H;
	scrollCnt = 0;
	currX = boxL;

	if (!fontID) {
		// Create Texture
		glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
		glGenTextures(1, &fontID);
		glBindTexture(GL_TEXTURE_2D, fontID);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexImage2D(
			GL_TEXTURE_2D,
			0,
			GL_LUMINANCE_ALPHA,
			FONT_TEX_W,
			FONT_TEX_H,
			0,
			GL_LUMINANCE_ALPHA,
			GL_UNSIGNED_BYTE,
			(void *)fontData);
	}

	// Set Color
	SET_COLOR(color, 255, 255, 255, 255);

	// Set Mode
	mode = 0;
}

//---------------------------------------------------------------------------
// Load Font Texture and set current Matrix to Screen Space
//---------------------------------------------------------------------------
void TextBox::Begin() {
	// Push the neccessary Matrices on the stack
	glMatrixMode(GL_PROJECTION);
	glPushMatrix();
		glLoadIdentity();
		glOrtho(0.0, 640.0, 480.0, 0.0, -1.0, 1.0);
	glMatrixMode(GL_MODELVIEW);
	glPushMatrix();
		glLoadIdentity();

	// Push the neccessary Attributes on the stack
	glPushAttrib(GL_TEXTURE_BIT|GL_ENABLE_BIT);

	glBindTexture(GL_TEXTURE_2D, fontID);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 
	glEnable(GL_TEXTURE_2D);

	// Always Draw in Front
	glDisable(GL_DEPTH_TEST);
	glDisable(GL_CULL_FACE);

	if (!(mode & TEXT_DRAW_BACKGROUND)) {
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	}
}


//---------------------------------------------------------------------------
// Remove Screen Matrix
//---------------------------------------------------------------------------
void TextBox::End() {
	// Return to previous Matrix and Attribute states. Easy cleanup!
	glMatrixMode(GL_PROJECTION);
	glPopMatrix();
	glMatrixMode(GL_MODELVIEW);
	glPopMatrix();
	glPopAttrib();
}

//---------------------------------------------------------------------------
// Draw a string at a given coordinate
//---------------------------------------------------------------------------
void TextBox::DrawStr(int x, int y, char * str) {
	Begin();
	DrawStr(x, y, 0, 0, str);
	End();
}

//---------------------------------------------------------------------------
// Draw the Text given to TextBoxPrintf()
//---------------------------------------------------------------------------
void TextBox::Draw() {
	Paginate();
	Begin();
	if(mode & TEXT_DRAW_BOX) DrawBoundingBox();
	DrawStr(boxL, boxT, 1, boxB, drawBufferPtr);
	End();
}

//---------------------------------------------------------------------------
// Draw a string at a given position in screen space
//---------------------------------------------------------------------------
void TextBox::DrawStr(int x, int y, int maxFlag, int maxY, char* string) {
	int cursorX;
	int cursorY;
	char* cP = string;
	int index;
	int s, t;

	cursorX = x;
	cursorY = y;

	glColor4ub(color.r, color.g, color.b, color.a);
	glBegin(GL_QUADS);

	// Parse the String
	while (*cP != '\0') {
		// Visible characters
		if ( ' ' == *cP && !(mode & TEXT_DRAW_SPACES)) {
			cursorX += FONT_DRAW_W;
		}
		else if ( ' ' <= *cP && *cP <= '~' ) {
			index = *cP - ' ';
			s = ( index % 8 ) * FONT_W;
			t = ( index / 8 ) * FONT_H;
			glTexCoord2f((float)(s       )/FONT_TEX_W, (float)(t           )/FONT_TEX_H);
			glVertex3s(cursorX            , cursorY            , 0);
			glTexCoord2f((float)(s       )/FONT_TEX_W, (float)(t+FONT_H + 1)/FONT_TEX_H);
			glVertex3s(cursorX            , cursorY+FONT_DRAW_H, 0);
			glTexCoord2f((float)(s+FONT_W)/FONT_TEX_W, (float)(t+FONT_H + 1)/FONT_TEX_H);
			glVertex3s(cursorX+FONT_DRAW_W, cursorY+FONT_DRAW_H, 0);
			glTexCoord2f((float)(s+FONT_W)/FONT_TEX_W, (float)(t           )/FONT_TEX_H);
			glVertex3s(cursorX+FONT_DRAW_W, cursorY            , 0);
			cursorX += FONT_DRAW_W;
		}
		if ( *cP == '\n' ) {
			cursorX = x;
			cursorY += FONT_DRAW_H;
			if (maxFlag && cursorY + FONT_DRAW_H > maxY) break;
		}
		cP++;
	}

	glEnd( );
}

//---------------------------------------------------------------------------
// Draw Bounding Box
//---------------------------------------------------------------------------
void TextBox::DrawBoundingBox() {
	glColor4f(0.0, 0.0, 0.0, 1.0);
	glBegin(GL_QUADS);
	glVertex3s(boxL, boxT, 0);
	glVertex3s(boxR, boxT, 0);
	glVertex3s(boxR, boxB, 0);
	glVertex3s(boxL, boxB, 0);
	glEnd( );
}

//---------------------------------------------------------------------------
// This function will concatinate a formated string the a TextBox
//---------------------------------------------------------------------------
void TextBox::FormatStrCat(char * str) {
	char buff[MAX_STR];
	char buff2[MAX_STR];
	char * cP;
	char * cP2;

	strcpy(buff, str);
	cP = buff;

	// Format String for caption
	// Parse the String
	while (*cP != '\0') {
		// Visible characters
		if ( ' ' <= *cP && *cP <= '~' ) {
			currX += FONT_DRAW_W;
		}
		else if ( *cP == '\n' ) {
			currX = boxL; 
		}

		// Wrap 
		if (currX >= boxR) {
			cP++;
			// Find the last space
			if (mode & TEXT_WRAP_SPACES) {
				while(cP > buff && *cP != ' ') cP--;
			}
			strcpy(buff2, cP);
			*cP++ = '\n';
			*cP = '\0';
			// Eliminate Space
			if (mode & TEXT_WRAP_SPACES && buff2[0] == ' ') cP2 = &buff2[1];
			else cP2 = buff2;
			strcat(cP, cP2);
			currX = boxL;
		} 
		else {
			cP++;
		}
	}

	// Make sure it fits in the text buffer by removing
	// strings at the top of the buffer.
	cP = buffer;
	while (strlen(cP) + strlen(buff) > MAX_STR) {
		cP = strchr(cP, '\n');
		if( !cP ) {
			assert( !"TextBox::FormatStrCat: string too long!!!" );
		}
		cP++;
	}
	// If there are strings that need to be removed. Do so.
	if (cP != buffer) {
		strcpy(buff2, cP);
		strcpy(buffer, buff2);
	}
	// Now there is space. So, concatinate.
	strcat(buffer, buff); 
}

//---------------------------------------------------------------------------
// Paginate the text Box
//---------------------------------------------------------------------------
void TextBox::Paginate() {
	int newLineCnt = 0;
	int pageNewLineCnt;
	char * cP;

	// Calculate the number of new lines from the bottom we want
	pageNewLineCnt = pageLineCnt + scrollCnt;

	// Starting at the end of the string count the number of newlines backwards
	cP = strchr(buffer, '\0');
	while(cP > buffer) {
		if(*cP == '\n') newLineCnt++;
		if (newLineCnt == pageNewLineCnt) {
			cP++;
			break;
		}
		cP--;
	}
	if (cP == buffer && newLineCnt > pageLineCnt) 
		scrollCnt = newLineCnt - pageLineCnt + 1;