1 //
2 // Book: OpenGL(R) ES 2.0 Programming Guide
3 // Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
4 // ISBN-10: 0321502795
5 // ISBN-13: 9780321502797
6 // Publisher: Addison-Wesley Professional
7 // URLs: http://safari.informit.com/9780321563835
8 // http://www.opengles-book.com
9 //
10
11 // MultiTexture.c
12 //
13 // This is an example that draws a quad with a basemap and
14 // lightmap to demonstrate multitexturing.
15 //
16 #include <stdlib.h>
17 #include "esUtil.h"
18
19 typedef struct
20 {
21 // Handle to a program object
22 GLuint programObject;
23
24 // Attribute locations
25 GLint positionLoc;
26 GLint texCoordLoc;
27
28 // Sampler locations
29 GLint baseMapLoc;
30 GLint lightMapLoc;
31
32 // Texture handle
33 GLuint baseMapTexId;
34 GLuint lightMapTexId;
35
36 } UserData;
37
38
39 ///
40 // Load texture from disk
41 //
LoadTexture(char * fileName)42 GLuint LoadTexture ( char *fileName )
43 {
44 int width,
45 height;
46 char *buffer = esLoadTGA ( fileName, &width, &height );
47 GLuint texId;
48
49 if ( buffer == NULL )
50 {
51 esLogMessage ( "Error loading (%s) image.\n", fileName );
52 return 0;
53 }
54
55 glGenTextures ( 1, &texId );
56 glBindTexture ( GL_TEXTURE_2D, texId );
57
58 glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer );
59 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
60 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
61 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
62 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
63
64 free ( buffer );
65
66 return texId;
67 }
68
69
70
71 ///
72 // Initialize the shader and program object
73 //
Init(ESContext * esContext)74 int Init ( ESContext *esContext )
75 {
76 UserData *userData = esContext->userData;
77 GLbyte vShaderStr[] =
78 "attribute vec4 a_position; \n"
79 "attribute vec2 a_texCoord; \n"
80 "varying vec2 v_texCoord; \n"
81 "void main() \n"
82 "{ \n"
83 " gl_Position = a_position; \n"
84 " v_texCoord = a_texCoord; \n"
85 "} \n";
86
87 GLbyte fShaderStr[] =
88 "precision mediump float; \n"
89 "varying vec2 v_texCoord; \n"
90 "uniform sampler2D s_baseMap; \n"
91 "uniform sampler2D s_lightMap; \n"
92 "void main() \n"
93 "{ \n"
94 " vec4 baseColor; \n"
95 " vec4 lightColor; \n"
96 " \n"
97 " baseColor = texture2D( s_baseMap, v_texCoord ); \n"
98 " lightColor = texture2D( s_lightMap, v_texCoord ); \n"
99 " gl_FragColor = baseColor * (lightColor + 0.25); \n"
100 "} \n";
101
102 // Load the shaders and get a linked program object
103 userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
104
105 // Get the attribute locations
106 userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" );
107 userData->texCoordLoc = glGetAttribLocation ( userData->programObject, "a_texCoord" );
108
109 // Get the sampler location
110 userData->baseMapLoc = glGetUniformLocation ( userData->programObject, "s_baseMap" );
111 userData->lightMapLoc = glGetUniformLocation ( userData->programObject, "s_lightMap" );
112
113 // Load the textures
114 userData->baseMapTexId = LoadTexture ( "basemap.tga" );
115 userData->lightMapTexId = LoadTexture ( "lightmap.tga" );
116
117 if ( userData->baseMapTexId == 0 || userData->lightMapTexId == 0 )
118 return FALSE;
119
120 glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
121 return TRUE;
122 }
123
124 ///
125 // Draw a triangle using the shader pair created in Init()
126 //
Draw(ESContext * esContext)127 void Draw ( ESContext *esContext )
128 {
129 UserData *userData = esContext->userData;
130 GLfloat vVertices[] = { -0.5f, 0.5f, 0.0f, // Position 0
131 0.0f, 0.0f, // TexCoord 0
132 -0.5f, -0.5f, 0.0f, // Position 1
133 0.0f, 1.0f, // TexCoord 1
134 0.5f, -0.5f, 0.0f, // Position 2
135 1.0f, 1.0f, // TexCoord 2
136 0.5f, 0.5f, 0.0f, // Position 3
137 1.0f, 0.0f // TexCoord 3
138 };
139 GLushort indices[] = { 0, 1, 2, 0, 2, 3 };
140
141 // Set the viewport
142 glViewport ( 0, 0, esContext->width, esContext->height );
143
144 // Clear the color buffer
145 glClear ( GL_COLOR_BUFFER_BIT );
146
147 // Use the program object
148 glUseProgram ( userData->programObject );
149
150 // Load the vertex position
151 glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT,
152 GL_FALSE, 5 * sizeof(GLfloat), vVertices );
153 // Load the texture coordinate
154 glVertexAttribPointer ( userData->texCoordLoc, 2, GL_FLOAT,
155 GL_FALSE, 5 * sizeof(GLfloat), &vVertices[3] );
156
157 glEnableVertexAttribArray ( userData->positionLoc );
158 glEnableVertexAttribArray ( userData->texCoordLoc );
159
160 // Bind the base map
161 glActiveTexture ( GL_TEXTURE0 );
162 glBindTexture ( GL_TEXTURE_2D, userData->baseMapTexId );
163
164 // Set the base map sampler to texture unit to 0
165 glUniform1i ( userData->baseMapLoc, 0 );
166
167 // Bind the light map
168 glActiveTexture ( GL_TEXTURE1 );
169 glBindTexture ( GL_TEXTURE_2D, userData->lightMapTexId );
170
171 // Set the light map sampler to texture unit 1
172 glUniform1i ( userData->lightMapLoc, 1 );
173
174 glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices );
175
176 eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface );
177 }
178
179 ///
180 // Cleanup
181 //
ShutDown(ESContext * esContext)182 void ShutDown ( ESContext *esContext )
183 {
184 UserData *userData = esContext->userData;
185
186 // Delete texture object
187 glDeleteTextures ( 1, &userData->baseMapTexId );
188 glDeleteTextures ( 1, &userData->lightMapTexId );
189
190 // Delete program object
191 glDeleteProgram ( userData->programObject );
192 }
193
194
main(int argc,char * argv[])195 int main ( int argc, char *argv[] )
196 {
197 ESContext esContext;
198 UserData userData;
199
200 esInitContext ( &esContext );
201 esContext.userData = &userData;
202
203 esCreateWindow ( &esContext, "MultiTexture", 320, 240, ES_WINDOW_RGB );
204
205 if ( !Init ( &esContext ) )
206 return 0;
207
208 esRegisterDrawFunc ( &esContext, Draw );
209
210 esMainLoop ( &esContext );
211
212 ShutDown ( &esContext );
213 }
214