Direct3D 8 - Vertex Shader - Version Differences

Last edited 2026-01-27

Each version supports a different number of maximum instruction slots.

It's important to use the D3D8 Vertex Shader (vs.1.0 or vs.1.1).

Using (vs_1_0 or vs_1_1) instead will result in the effect not working.

The meaning of colors in the Type, Version and Working column:

Vertex Shader Version Comparison (Wikipedia)

">= 96" for Number constant registers:

• The specification guarantees at least 96 constant registers.
• The GPU can have more, but not less.

• Number of instruction slots - The maximum number of assembly instructions (instruction slots) that a saved vertex shader program can contain.
• Max number of instructions executed - The maximum number of instructions the GPU can execute for a single vertex when running a vertex shader.
• Instruction predication - A predicate instruction mechanism that allows conditional execution without expensive branching: instructions marked with a predicate write their result only if the predicate is true.
• Temp register - Temporary registers (r0, r1, ...) are used to store intermediate values ​​of shader computations (local variables). The limit on the number of temp registers determines how much intermediate data can be stored without additional cost.
• Number constant registers - Number of constant registers intended for values ​​sent from the application (e.g. matrices, light positions).
• Address register - Address register (e.g. a0) used for indirect addressing/tables.
• Static flow control - Loops/conditions that the compiler can unroll or optimize because their number/nature is known at compilation.
• Dynamic flow control - True conditions and loops depending on data calculated at runtime (if/else, while, for with variable condition) - that is, control flow depending on values ​​calculated during shader execution.
• Dynamic flow control depth - Maximum allowed nesting depth for dynamic control statements (if/loop etc.) - This determines how deep data-dependent conditions/loops can be nested.
• Vertex texture fetch - Ability to sample textures inside the vertex shader.
• Number of texture samplers - The number of available texture samplers/slots that the vertex shader can use for sampling (if the VF is capable of fetching textures).
• Geometry instancing support - Geometry instantiation support: ability to read instance ID and draw multiple copies of the same mesh with different parameters in the vertex shader.
• Bitwise Operators - Support for bitwise logical operations (AND, OR, XOR, bit shifts <<, >>).
• Native Integers - Support for integer types (int), the lack of which means that everything is a floating-point number (float), which makes precision difficult.

Created with the Personal Edition of HelpNDoc: Make Documentation Review a Breeze with HelpNDoc's Advanced Project Analyzer