我尝试在 1 个片段着色器中访问 2 个纹理。
为此,我使用以下代码设置了 2 个纹理:
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, vbuff);
glTexCoordPointer(2, GL_FLOAT, 0, tbuff);
glActiveTextureARB(GL_TEXTURE0_ARB);
glBindTexture(GL_TEXTURE_2D, texture0);
glEnable(GL_TEXTURE_2D);
glActiveTextureARB(GL_TEXTURE1_ARB);
glBindTexture(GL_TEXTURE_2D, texture1);
glEnable(GL_TEXTURE_2D);
我尝试将它们与以下片段着色器结合起来:
uniform sampler2D tex0;
uniform sampler2D tex1;
void main()
{
vec4 texval1 = texture2D(tex0, TextureCoordOut);
vec4 texval2 = texture2D(tex1, TextureCoordOut);
gl_FragColor = 0.5*(texval1 + texval2)
}
不知何故,这不起作用,它只显示第二个纹理。
PS:我正在 Windows7 上开发着色器,但想在 Android 设备上使用 C++ 代码和带有 Android NDK 的着色器。
编辑:我让它工作,我在这里发布代码,以便其他人可以从中受益:
顶点着色器
varying vec2 TextureCoordOut;
void main()
{
gl_Position = ftransform();
TextureCoordOut = vec2(gl_MultiTexCoord0);
}
片段着色器
varying mediump vec2 TextureCoordOut;
uniform sampler2D tex0;
uniform sampler2D tex1;
void main()
{
gl_FragColor = texture2D(tex0, TextureCoordOut) * texture2D(tex1, TextureCoordOut);
}
使成为
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, vbuff); //2 dimensional vertex buffer
glTexCoordPointer(2, GL_FLOAT, 0, tbuff); // 2 dimensional textures
glColor4f(1, 1, 1, 1);
glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, mapid1);
glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, mapid2);
glUseProgram(shader);
glUniform1i(glGetUniformLocation(gfx.prog, "tex0"), 0); //GL_TEXTURE0
glUniform1i(glGetUniformLocation(gfx.prog, "tex1"), 1); //GL_TEXTURE1
render....
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);