Linking 2 textures, see only 1

Question

I am trying to bind 2 textures for my shader. But for some reason, it always seems like the last image I defined. Am I doing something wrong?

GLuint textures[2]; glEnable(GL_TEXTURE_2D); glGenTextures(2, textures); glBindTexture(GL_TEXTURE_2D, textures[0]); glfwLoadTexture2D("C:\\front.tga", GLFW_BUILD_MIPMAPS_BIT); glBindTexture(GL_TEXTURE_2D, textures[1]); glfwLoadTexture2D("C:\\reflect.tga", GLFW_BUILD_MIPMAPS_BIT); 

In this case, I see 'reflect.tga' for reflection and refraction in my shader ...

 const vec3 Xunitvec = vec3 (1.0, 0.0, 0.0); const vec3 Yunitvec = vec3 (0.0, 1.0, 0.0); uniform vec3 BaseColor; uniform float Depth; uniform float MixRatio; // need to scale our framebuffer - it has a fixed width/height of 2048 uniform float FrameWidth; uniform float FrameHeight; uniform sampler2D EnvMap; uniform sampler2D RefractionMap; varying vec3 Normal; varying vec3 EyeDir; varying vec4 EyePos; varying float LightIntensity; void main (void) { // Compute reflection vector vec3 reflectDir = reflect(EyeDir, Normal); // Compute altitude and azimuth angles vec2 index; index.y = dot(normalize(reflectDir), Yunitvec); reflectDir.y = 0.0; index.x = dot(normalize(reflectDir), Xunitvec) * 0.5; // Translate index values into proper range if (reflectDir.z >= 0.0) index = (index + 1.0) * 0.5; else { index.t = (index.t + 1.0) * 0.5; index.s = (-index.s) * 0.5 + 1.0; } // if reflectDir.z >= 0.0, s will go from 0.25 to 0.75 // if reflectDir.z < 0.0, s will go from 0.75 to 1.25, and // that OK, because we've set the texture to wrap. // Do a lookup into the environment map. vec3 envColor = vec3 (texture2D(EnvMap, index)); // calc fresnels term. This allows a view dependant blend of reflection/refraction float fresnel = abs(dot(normalize(EyeDir), Normal)); fresnel *= MixRatio; fresnel = clamp(fresnel, 0.1, 0.9); // calc refraction vec3 refractionDir = normalize(EyeDir) - normalize(Normal); // Scale the refraction so the z element is equal to depth float depthVal = Depth / -refractionDir.z; // perform the div by w float recipW = 1.0 / EyePos.w; vec2 eye = EyePos.xy * vec2(recipW); // calc the refraction lookup index.s = (eye.x + refractionDir.x * depthVal); index.t = (eye.y + refractionDir.y * depthVal); // scale and shift so we're in the range 0-1 index.s = index.s / 2.0 + 0.5; index.t = index.t / 2.0 + 0.5; // as we're looking at the framebuffer, we want it clamping at the edge of the rendered scene, not the edge of the texture, // so we clamp before scaling to fit float recip1k = 1.0 / 2048.0; index.s = clamp(index.s, 0.0, 1.0 - recip1k); index.t = clamp(index.t, 0.0, 1.0 - recip1k); // scale the texture so we just see the rendered framebuffer index.s = index.s * FrameWidth * recip1k; index.t = index.t * FrameHeight * recip1k; vec3 RefractionColor = vec3 (texture2D(RefractionMap, index)); // Add lighting to base color and mix vec3 base = LightIntensity * BaseColor; envColor = mix(envColor, RefractionColor, fresnel); envColor = mix(envColor, base, 0.2); gl_FragColor = vec4 (envColor, 1.0); } 

Answer 1

A sampler unit does not bind a texture object, but a texture block. And texture objects are tied to texture units. Thus, the sequence of binding the texture to the shader

 glActiveTexture(GL_TEXTURE0 + texture_unit1); glBindTexture(GL_TEXTURE_..., texture_object1); glActiveTexture(GL_TEXTURE0 + texture_unit2); glBindTexture(GL_TEXTURE_..., texture_object2); glUniform1i(sampler1_location, texture_unit1); glUniform1i(sampler2_location, texture_unit2); 

Texture units are in the range 0 ... GL_MAX_TEXTURE_UNITS .