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POMultiple textures in GLSL - only one works
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copied!<p>My problem is getting more than one texture accessible in a GLSL shader. Here's what I'm doing:</p> <p>Shader:</p> <pre><code>uniform sampler2D sampler0; uniform sampler2D sampler1; uniform float blend; void main( void ) { vec2 coords = gl_TexCoord[0]; vec4 col = texture2D(sampler0, coords); vec4 col2 = texture2D(sampler1, coords); if (blend > 0.5){ gl_FragColor = col; } else { gl_FragColor = col2; } }; </code></pre> <p>So, I simply choose between the two color values based on a uniform variable. Simple enough (this is a test), but instead of the expected behavior, I get all black <strike>when blend <= 0.5</strike>.</p> <p>OpenGL code:</p> <pre><code>m_sampler0location = m_shader.FindUniform("sampler0"); m_sampler1location = m_shader.FindUniform("sampler1"); m_blendlocation = m_shader.FindUniform("blend"); glActiveTexture(GL_TEXTURE0); glEnable(GL_TEXTURE_2D); m_extensions.glUniform1iARB(m_sampler0location, 0); glBindTexture(GL_TEXTURE_2D, Texture0.Handle); glActiveTexture(GL_TEXTURE1); glEnable(GL_TEXTURE_2D); m_extensions.glUniform1iARB(m_sampler1location, 1); glBindTexture(GL_TEXTURE_2D, Texture1.Handle); glBegin(GL_QUADS); //lower left glTexCoord2f(0, 0); glVertex2f(-1.0, -1.0); //upper left glTexCoord2f(0, maxCoords0.t); glVertex2f(-1.0, 1.0); //upper right glTexCoord2f(maxCoords0.s, maxCoords0.t); glVertex2f(1.0, 1.0); //lower right glTexCoord2f(maxCoords0.s, 0); glVertex2f(1.0, -1.0); glEnd() </code></pre> <p>The shader is compiled and bound before all this. All the sanity checks in that process indicate that it goes ok. <strike>As I said, the value of <code>col</code> in the shader program reflects fragments from a texture; the value of <code>col2</code> is black. The texture that is displayed is the last active texture - if I change the last <code>glBindTexture</code> to bind <code>Texture0.Handle</code>, the texture changes.</strike> Fixed according to Bahbar's reply.</p> <p>As it is, the scene renders all black, even if I add something like <code>gl_FragColor.r = blend;</code> as the last line of the shader. But, if I comment out the call <code>glActiveTexture(GL_TEXTURE1);</code>, the shader works again, and the same texture appears in both sampler0 and sampler1. </p> <p>What's going on? The line in question, <code>glActiveTexture(GL_TEXTURE1);</code>, seems to work just fine, as evidenced by a subsequent <code>glGetIntegerv(GL_ACTIVE_TEXTURE, &anint)</code>. Why does it break everything so horribly? I've already tried upgrading my display drivers.</p>

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