Let’s look at #1: Considering every object might have its own material, it involves a lot of glUseProgram calls. This isn’t that big of a deal, really. Swapping programs is hard, but you’d be swapping textures too, so it’s not like you’re not already changing important state. Implies the creation of a lot of shaderprogram … Read more
First of all there are tons of algorithms and techniques to generate a glow effect. I just want to present one possibility. Create a Material that is luminescent. For this I use a modified Blinn-Phong light model, where the direction to the light source is always the inverse direction of the normal vector of the … Read more
If the condition is uniform (i.e. constant for the entire pass), then the branch is essentially free because the framework will essentially compile two versions of the shader (branch taken and not) and choose one of these for the entire pass based on your input variable. In this case, definitely go for the if statement … Read more
§ 4.1 Basic Types The OpenGL Shading Language supports the following basic data types, grouped as follows: bool a conditional type, taking on values of true or false bvec2 a two-component Boolean vector bvec3 a three-component Boolean vector bvec4 a four-component Boolean vector … § 4.1.2 Booleans To make conditional execution of code easier to … Read more
The relevant input data to your problem are the texture coordinates. Tangent and Binormal are vectors locally parallel to the object’s surface. And in the case of normal mapping they’re describing the local orientation of the normal texture. So you have to calculate the direction (in the model’s space) in which the texturing vectors point. … Read more
As an addition to this answer, here is a simple geometry shader which will let you visualize your normals. Modify the accompanying vertex shader as needed based on your attribute locations and how you send your matrices. But first, a picture of a giant bunny head from our friend the Stanford bunny as an example … Read more
Look at the rock of the bottom of that last image – it’s got sandy-colored lines going through it. Presumably, you are drawing the sand first, then the rock on top. This tells me it’s not “black lines being drawn” through the textures, but that parts of the textures are not being drawn. Since it … Read more
I figured out your problem: you are rendering to the same buffer that you’re sourcing your vertex data. glBindVertexArray(vaoPass2); I think you meant vaoPass1 From the spec: Buffers should not be bound or in use for both transform feedback and other purposes in the GL. Specifically, if a buffer object is simultaneously bound to a … Read more
Variables shared between both examples: GLint i; GLint count; GLint size; // size of the variable GLenum type; // type of the variable (float, vec3 or mat4, etc) const GLsizei bufSize = 16; // maximum name length GLchar name[bufSize]; // variable name in GLSL GLsizei length; // name length Attributes glGetProgramiv(program, GL_ACTIVE_ATTRIBUTES, &count); printf(“Active Attributes: … Read more
You can use multiple shaders, but to switch between them can be quite costly so the recommended practise is to draw every object of a shader, then switch to the next shader and draw all the objects using that one and so on. To switch between shaders, you call glUseProgram().